M1 iMac not charging keyboard or mouse

Please restart the computer in Safe Mode per the directions in the  How to use safe mode on your Mac - Apple Support link.

Note: If you are using a wireless keyboard please either plug it in using the supplied Lightning cable that shipped with it. If you are using a legacy keyboard or a third-party keyboard that does not have re-charging abilities, please use any USB keyboard. Also note that a Safe Mode restart may require you to hold down the shift key for up to 5 minutes before the computer starts in Safe Mode. You will know it is in Safe Mode when you see “Safe Mode” in the upper right of the display.

If you continue to have a problem, please advise. By chance is there any third party antivirus, cleaning or other third party maintenance apps installed on the computer??

CMM may very well be your problem! Please read below:

The best antivirus, cleaning app, and overall maintenance app for Mac OS is Mac OS itself. All you need to do with Mac OS to keep it secure and running well is to keep it up-to-date and do periodic (about 1x per week) restarts. Other than that, leave it alone. Adding third party antivirus, cleaning, security and other types of maintenance apps to Mac OS adds no additional level of security. The only thing these apps do is have the opposite affect users want. They make Mac OS slow, unstable, generate odd behavior (much like you are experiencing) and make Mac OS appear buggy.

Please locate the developers uninstall instructions for CleanMyMac and follow to the letter. Then restart in Safe Mode per the directions in Use safe mode to isolate issues with your Mac  and then restart normally.

After you have restarted in Safe Mode, please restart normally and check the charging about 2-3 hours later to see if it is charging correctly.

Also, you did not answer the question, "By chance is there any third party antivirus, cleaning or other third party maintenance apps installed on the computer??" please do.