In a sign that service industry workers continue to have a strong interest in unionizing after successful votes at Starbucks, REI and Amazon, employees at a Trader Joe’s in western Massachusetts have filed for a union election. If they win, they will create the only union at Trader Joe’s, which has more than 500 locations and 50,000 employees nationwide.

The filing with the National Labor Relations Board late Tuesday seeks an election involving about 85 employees who would form an independent union, Trader Joe’s United, rather than affiliate with an established labor organization. That echoes the independent union created by Amazon workers on Staten Island and the worker-led organizing at Starbucks.

“Over the past however many years, changes have been happening without our consent,” said Maeg Yosef, an 18-year employee of the store who is a leader of the union campaign. “We wanted to be in charge of the whole process, to be our own union. So we decided to go independent.”

Ms. Yosef said the union had support from over 50 percent of workers at the store, known as crew members.

“We have always said we welcome a fair vote and are prepared to hold a vote if more than 30 percent of the crew wants one,” said a company spokeswoman, Nakia Rohde, alluding to the N.L.R.B. threshold for an election. “We are not interested in delaying the process in any way.”

The company shared a similar statement with workers after they announced their intention to unionize in mid-May.

In explaining their decision, Ms. Yosef and four colleagues, all of whom have been with the company for at least eight years, cited changes that had made their benefits less generous over time, as well as health and safety concerns, many of which were magnified during the pandemic.

“This is probably where we get to all of these things coming together,” said Tony Falco, another worker involved in the union campaign, alluding to Covid-19.

Mr. Falco said the store, in Hadley, took several reassuring steps during the first 12 to 15 months of the pandemic. Management enforced masking requirements and restrictions on the number of customers who could be in the store at once. It allowed workers to take leaves of absence while continuing to receive health insurance and gave workers additional “thank you” pay as high as $4 per hour.

But Mr. Falco and others said the company was too quick to roll back many of these measures — including additional pay — as vaccines became widely available last year, and noted that the store had suffered Covid outbreaks in the past several weeks after masking became laxer. The store followed the policy of the local health board, which altered its mask mandate at various points, lifting it most recently in March.

Some employees were also upset that the company did not inform them that the state had passed a law requiring employers to provide up to five paid days off for workers who missed work because of Covid.

“It was in effect seven months, and they never announced it,” Ms. Yosef said. “I figured that out at the end of December, early January.”

Ms. Rohde, the spokeswoman, said this account was incorrect, but four other employees who support the union also said the company had not told them of the policy.

Trader Joe’s has generally resisted unionization over the years, including earlier in the pandemic. In March 2020, the chief executive, Dan Bane, sent employees a letter referring to “the current barrage of union activity that has been directed at Trader Joe’s” and complaining that union advocates “clearly believe that now is a moment when they can create some sort of wedge in our company through which they can drive discontent.”

The company’s response to the current campaign appears somewhat less hostile, though union organizers have recently filed charges of unfair labor practices, such as asking employees to remove pro-union pins.

Several employees said a broader issue was underlying their frustrations: what they saw as the company’s evolution from a niche outlet known for pampering customers and treating employees generously to an industrial-scale chain that is more focused on the bottom line.

The company’s employee handbook urges workers to provide a “Wow customer experience,” which it defines as “the feelings a customer gets about our delight that they are shopping with us.” But longtime employees say the company, which is privately held, has gradually become stingier with workers.

For years, the company offered health care widely to part-timers. In the early 2010s, the company raised the average weekly hours that employees needed to qualify for full health coverage to 30 from roughly 20, informing those who no longer qualified that they could receive coverage under the federal Affordable Care Act instead. (The company dropped the threshold to 28 hours more recently.)

“It was done under the guise of ‘You can get these plans, they’re the same plans,’ but they were not the same plans,” said Sarah Yosef, the Hadley store’s manager at the time, who later stepped back from the role and is now a frontline worker there.

“I had to sit there individually with crew members saying you’re going to be losing health insurance,” added Ms. Yosef, who is married to Maeg Yosef.

Retirement benefits have followed a similar trajectory: Around the same time, Trader Joe’s lowered its retirement contribution to 10 percent of an employee’s earnings from about 15 percent, for employees 30 and older. Beginning with last year’s benefit, the company lowered the percentage again for many workers, who saw the contribution fall to 5 percent. The company is no longer specifying any set amount.

Ms. Rohde, the spokeswoman, said the change was partly a response to indications from many workers that they would prefer a bonus to a retirement contribution.

Workers said the company’s determination to provide an intimate shopping experience had often come at their expense amid a rapid increase in business over the past decade, and then again with the resurgence of business as pandemic restrictions lifted.

For example, Trader Joe’s doesn’t have conveyor belts at checkout lines and instructs cashiers to reach into customers’ carts or baskets to unload items. This can appear to personalize the service but takes a physical toll on workers, who typically bend over hundreds of times during a shift.

(The company asks workers to perform different tasks throughout the day so they are not constantly ringing up customers.)

Maeg Yosef and her co-workers began discussing the union campaign over the winter, angry over the store’s failure to publicize the state-mandated paid leave benefit and the change in retirement benefits, and some have drawn inspiration from the successful union elections at Starbucks, Amazon and REI.

Their union campaign may also benefit from the same leverage that workers at those companies enjoyed as a result of the relatively tight job market.

“People just keep leaving — I know they want to hire people now,” Maeg Yosef said. “It’s hard to keep people around.”