The “shoppers” who complete Instacart grocery delivery orders went on strike this week, alleging significant problems with the app’s structure that are familiar throughout the gig economy. As independent contractors, the shoppers are subject to unpredictable pay and have no traditional workplace protections. Now, they say the app’s designers are making it actively harder for them to make ends meet.

The strike was announced in a Medium Post, addressed to Instacart CEO Apoorva Mehta, which outlined years of subtle changes that have left workers worse off each time. The workers say that the app’s interface has been repeatedly manipulated to discourage tipping, or to seemingly replace it with a 10% service fee that is controlled by the company. In 2018, that conflict came to a head, and the company had to publicly apologize for withholding worker tips and service charges, calling the problem a “bug.” Workers previously won a $4.6 million lawsuit over the app’s explanation of the service fee that mistakenly led users to believe the fee benefited the workers. Beyond tipping, the shoppers have called out changes to their direct compensation, as the company moved from a transparent commission to an algorithmic “black box” model last year that seemingly reduced base pay if a worker received tips. Another apology followed.

As Instacart’s problems persist, the “shoppers” continue to publicize and explain how subtle interface changes on the app affect their daily lives. This time, they allege retaliation. This week, the app cut the “quality bonus” paid to shoppers, stating that it has done little to improve outcomes. But workers say this bonus constituted a major portion of their compensation, and say “there is no doubt … that this is retaliatory.”

A full Medium post outlining the alleged retaliation has been removed by the site, which says it is “under investigation or in violation of the Medium Rules

In other food delivery news: a group of pizza delivery drivers who worked for Papa Johns in Ohio, Nevada, and North Carolina is able to progress in their lawsuit against Papa Johns for underpayment of wages linked to a failure to reimburse for driving expenses. The drivers allege that the pizza chain failed to properly compensate them for delivery expenses incurred from using their own cars to make deliveries and that their hourly wage is not high enough to “absorb” those costs without dipping below the legal minimum. Similar suits have been filed across the country in recent years against near all pizza chains, alleging serious problems in the industry.