I have the same issue with PHP8.0-apcu. Tried adding apc.enable_cli=1 to /etc/php/8.0/apache2/php.ini, /etc/php/8.0/cli/php.ini and /etc/php/8.0/mods-available/apcu.ini.
Even adding apc.shm_size=512M to /etc/php/8.0/mods-available/apcu.ini still no luck…
Some other posts suggest going to an earlier version of php, but I will wait for a solution for php8.0
Update (2 mins later):
sudo -u www-data php8.0 --define apc.enable_cli=1 /var/www/nextcloud/occ maintenance:repair
Worked!