FWIW there looks to be a new occ command in NC20 to address this without having to jump into sql commands:
security:bruteforce:reset
For the Linuxserverio docker, you’d want to bash into the container:
docker exec -it <container-name> bash
and run the command something like this:
sudo -u abc php /config/www/nextcloud/occ security:bruteforce:reset <ip>
I haven’t been able to confirm if this fixed it yet as the person who was affected by this uninstalled the app and hasn’t yet reinstalled, but I thought I would follow up with this method in case anyone else might find it simpler.