Fairphone have a beta testing process in place.
If a number of beta testers had this kind and level of failures, I’m pretty sure it would have come up before release.
Checking the SD card can’t hurt, SD cards are bound to fail somewhen in general, and additionally Android 10 at the latest (across vendors and devices) would prove even more problematic for incorporating it into Internal Storage than the concept is already.
If you didn’t do a factory reset or even a clean install already on the way when migrating, this option should be considered, too.