I guess if you check it periodically, like once a quarter or year, it would be ok. It might not effectively be too different than a HDD since you have to check that periodically too, but more often checks might be warranted due to aformentioed points in this thread about flash data retention and MicroSD reliability.
Most I would do is a write test followed by a read test, and then check the smart counters
That might be the culprit
It’s fine on most if not all USB thumb drives nowadays. Windows has disabled its write cache on removable devices since like 2016. It was more annoying than anything anyway since the cache just soaked up all the writes into system memory with no throttling. Then you could be sitting there for half an hour not knowing the progress of the writes on the drive if it was a slow flash drive.
For external SSDs it’s a must to do a safe removal since the drive’s write cache will almost always be enabled, or if it’s disabled the drive’s performance will tank. Not sure about DRAM-less SSDs though. Also, SSDs can corrupt more than just the data being modified, so the stakes are higher.
For external SMR hard drives the write cache will always be enabled since they basically can’t function without it, so it would be a good idea to do a safe removal then. Plus the drive gets shutdown cleanly. A surprise power cut makes the head slam back with the residual energy from the spinning platters and I’ve seen it kill a couple drives.
TL;DR thumb drives you can just yank on windows, everything else you should probably do a safe removal
Does it have ECC memory?
Yep, I’ve seen drives that are 100% green on SMART and self tests but operate slow as dirt. Although, of course, you’re going to want to make sure that it wasn’t the cable or something.