One time, Google randomly ceased payment processing for our app. When I reached out to them, the support staff were not at all helpful and said an "account specialist" would be needed and that they would forward the case along. Afterwards, I got an email saying that they would respond in 24-48 hours. After days of waiting, they finally message me asking for passport photos. I send them over, get another "24-48 hour message", and then two days later they reply back saying they want the exact same documents again. Insane! I send it again and mention that I already sent these. They wait two days and reply back that they actually want my co-founder's passport now. I reply back with that. Then they send another "please wait 24-48 hours" message.
At this point, I tried reaching out to friends at Google to see if they could escalate internally for me. A case got created, but two days later I get an email saying that this is something that the Google Pay team manages, not the Play Store team. Apparently, Google's org chart was my problem.
After all this, a response comes back saying "Your account is currently suspended you submitted documents which cannot be used to verify your account details. Our team has responded to you with specifics about what needs to be submitted in order for them to complete our review." Except they hadn't. I responded back about how both my cofounder and I submitted every document they asked for multiple times and answered all their questions to no avail. I pleaded with them to please let me speak to a human about this. After yet another agonizing 96 hours, our case was resolved and payment processing was re-enabled. We were bleeding money at the time and had been paying thousands of dollars a month to their ridiculous 30% highway robbery tax on subscriptions.
While not quite as bad, Apple blocked an app update because the current reviewer didn't like our subscription group separation. The only problem is that the app release in question had no such changes and the subscription group setup had already been approved in a previous release. The setup made sense and used common practices for A/B testing different prices, but the Apple agent we got on the phone with wouldn't have it. They insisted we release an update that would break existing subscribers to comply with their policies. Two bugfix updates were rejected for nonsensical reasons. We went through an escalation channel to get them out. When we submitted updates again, the reviewers magically had no more issues with things they'd already approved in the past.
Forcing a 30% cut isn't even the worst offense of these app stores. There's literally no easy recourse when things go wrong.