I have a 2016 MacBook Pro with TouchBar 500GB SSD, and I have had this happen when I first installed Big Sur. Try clearing cache. These steps are what I take and work all the time. Quit all apps (except essentials like Finder), including any (third party) apps in the menubar. This video summarises steps 2-3: https://drive.google.com/drive/folders/1RecawpaaGCyT9tZXT31D2XNuBVvp9EH_?usp=sharing On Finder (or on your desktop) click on Go. Hold Option or Alt and Click on Library. Go to Cache folder and delete EVERYTHING (in the Cache folder only) Restart If none of these steps help, your only hope is to see if the MacBook can self-determine if something is wrong: A Hardware Test A last resort may be to either Reinstall MacOS (either keeping your personal files or deleting them) Sorry if none of these help.

I have a 2016 MacBook Pro with TouchBar 500GB SSD. Some general solutions that may apply is doing a SMC and NVRAM reset. How to reset the SMC of your Mac Reset NVRAM or PRAM on your Mac If neither do anything try clearing cache. These steps are what I take and work all the time. Quit all apps (except essentials like Finder), including any (third party) apps in the menubar. This video summarises steps 2-3: https://drive.google.com/drive/folders/1RecawpaaGCyT9tZXT31D2XNuBVvp9EH_?usp=sharing On Finder (or on your desktop) click on Go. Hold Option or Alt and Click on Library. Go to Cache folder and delete EVERYTHING (in the Cache folder only) Restart If this doesn't fix it then Run a First Aid And if that alone doesn't help try running a First Aid in Safe Mode If none of these steps help, your only hope is to see if the MacBook can self-determine if something is wrong: A Hardware Test A last resort may be to either Reinstall MacOS (either keeping your personal files or deleting them) or replacing your SSD Sorry if none of these help.