not really on how it happens (having a log) or what exactly is changed for Android to see corruption. I have a hunch it’s due to the OTA process / somewhere in the recovery. Wrote on it in this thread - Help: Sd card corrupted after update to v1.0 (Galaxy s10+) - #2 by tcecyk
On boot there runs a filesystem check on it and as your FP3 has a newer incarnation of the driver (and exfatprogs) it will probably fix whatever it deemed corrupt. For the original poster: can’t find the gs290 fs driver sources to compare