From Seenda support:
The keyboard is compatible with computer systems below Mac OS11.6. If the computer system is the latest version of macOS Monterey 12.0.1, there may be compatibility issues. Some keys of our Bluetooth keyboard may have no function or function error.
Please long press “ESC” + “=” to restore factory settings, delete the Bluetooth connection name of keyboard on the computer connect list and re-pair, then press “FN” + “R” + “left shift” three buttons together to solve the issue.
My keyboard is now working as labeled!
Two new key sequences we may want to add the to manual:
'ESC' + '='
Hold down for 6 seconds to factory reset the keyboard
'FN' + 'r' + 'left shift'
To swap the Cmd and Option keys