I’ve noticed with the last couple versions of the official docker, unused docker volumes aren’t deleting whether you try:
docker volume prune
Or:
docker system prune -a --volumes
I had switched to using CTOP extensively to track my docker containers and using the CLI commands to handle upgrades and remove old containers and volumes with the commands above, but since that’s not working I switched back to using Portainer which allows you to easily select unused volumes and remove them. My SearxNG and Whoogle privacy search proxies install new volumes with new containers and I would have old volumes stack up pretty quickly taking up a lot of disk space maxing out my virtual machine instance, especially when SearxNG updates almost daily. So if you’re having the same issue it might be time to fire up Portainer which has improved quite a bit from the last time I used it, and if you have multiple docker machines you can install the Portainer Agent on the extras to access from one web interface.