Patches that break saves have been few if anything. Most of the updates that break the saves are from the DLC and you pretty much get a month’s heads up about it.
But with any game if there are big changes to mechanics or how major parts of the game work your saves are usually broken once you update. This isn’t new to PP.
Be grateful that this game has been getting as much attention from its devs in addressing issues or updating mechanics based on our feedback as it has. Some games go months without fixes.
Did we get the game we expected when it was first announced? No we didn’t. Does it still feel more like a beta? Maybe. But I don’t regret backing the game and look forward to seeing whats next down the line.
All in all having to start a new game every update is a small nuisance compared to dealing with bugs that might go on for months before getting looked into if ever