I updated to RouterOS 6.43.1 from version 6.41, and now the fans keep spinning every few minutes constantly.

One thing I noticed is under "System --> Health" the switch seems to think the CPU is at 40C, when the CPU usage is at 0-1%, and the unit itself is very cool to the touch.
My home office where this switch is located is kept on A/C set to 71F (21.6C). It's fairly cool, nothing else is near it on my desk etc.

This only become an issue literally now after installing the update.

No other changes to config etc.

I switched to SwOS and the fans aren't spinning as often as 6.43.1.

My CRS328 starts the fans at 40C, and stops them at about 36C. Quite annoying, as it goes on/off every 2 minutes or so. The CRS317 has no poE, so my theory was wrong: that this greater sensibility would be due the PoE internal PSUs.