2021 imac Thunderbolt/usb4 stop working after restart?

What all do you have connected to the Ports when you restart the iMac.

Too many devices or a buss powered hub could be overloading the port protection.

Try disconnecting some or all, then restart the iMac and test with less devices.

Please restart the compute in Safe Mode with the keyboard plugged into the back of the Mac with the charging cable that shipped with the computer. Then restart normally and retest.

BTW, do you have any of the following third party apps installed on your Mac?

·      Antivirus Apps

·      Cleaning Apps

·      Security Apps

·      VPN Apps

·      Maintenance Apps

Sorry, I mean what does System Preferences > Informations > System Reports > Thunderbolt/USB4 say?

Hi,

What does System Preferences > General > System reports > USB say?

Your welcome.