MySQL problem during upgrade nc15.0.0

I run Nexcloud in a docker compose setup. Usually upgrades run smoothly if I do:

docker-compose stop
docker-compose rm
docker-compose pull
docker compose up -d

However this time I get the maintenance page after doing so.

I connected with the db container and did a mysql_upgrade and everything looked fine.

I connect with the app container and run occ upgrade and this is the output:

sudo -u www-data php occ upgrade
Nextcloud or one of the apps require upgrade - only a limited number of commands are available
You may use your browser or the occ upgrade command to do the upgrade
Set log level to debug
Updating database schema
Doctrine\DBAL\Exception\DriverException: An exception occurred while executing 'ALTER TABLE oc_authtoken ADD password_invalid TINYINT(1) DEFAULT '0' NOT NULL':

SQLSTATE[HY000]: General error: 2006 MySQL server has gone away
Update failed
Maintenance mode is kept active
Reset log level

I am able to ping the DB server from the app container. I am also able to login to mysql on the mysql container using user nextcloud or root and the password from the /config/config.php file in the app container.

Do you have any idea how to proceed?