Since I have 10+ libraries and it could be up to 1+ day without crashes, by my calculations the experiment would take me at least a couple of weeks. So before starting it, I decided to try IFYates advice from here just in case. And it probably worked, at least I had no crashes for 5 full days (before it was almost every day).
The only place I could find info about the proper reinstall steps is here:
Since it’s titled as “FAQ 8: Uninstalling PMS - Reverting to a previous version” and I didn’t need to downgrade, I didn’t read this before. And I’d guess a lot of users also don’t try to reinstall it that way cause they’re too afraid of the “Uninstall” action, thinking it will remove their data or settings.
I think it would be useful to create a separate FAQ entry for “How to update/reinstall”, or add it as a troubleshooting step. But, in case similar issues may happen with the future versions, I think the best place to show a clean update routine on Synology would be here: https://www.plex.tv/media-server-downloads/#plex-media-server
