It's funny people tolerate this kind of stuff. I'd be out the door immediately, and I have been before. You don't have to work for companies that do this kind of insanity.
There is a reason we’ve decided what to work on. We have customers and a runway to consider, and targets we promised investors to reach. I also would like to work on fun stuff instead of fixing those bugs! That seems to be something you only understand later in your career though.
It's gonna get much, much harder to find the kind of laid-back company you favor, where you can work on whichever part of the code base you want, when you want. There's much less money sloshing around, and what's there needs to be spent on priority items.
Doing what the company needs done can also mean not taking orders from your PO. Depending on your situation, that could manifest as ignoring them, working around them, convincing them it was all their idea, directly challenging them, or going over their head. Skullduggery. Ass-kissing if necessary. Be a hero or a martyr in the end, but at least end each day with a clear conscience.
None of that being my preference, given the choice. All I expect from a PO is a collaborative relationship where I'm treated as an equal and not some member of the worker underclass who's just there to close tickets.
When the project collapses under its own weight as a consequence of the PO's own choices, is the PO going to take the blame? Is the PO going to help when production goes down? Will they working overtime to fix things? Who suffers? The PO? Not so much.