Is it possible to disable overuse of disk usage for all users at once?
For non-customized subscriptions:
1. Set Overuse policy option to Overuse is not allowed in Plesk > Service plans > Default > Resources
2. Press Update & Sync.
3. Repeat it for all service plans and synchronize them with their subscriptions.
For customized subscriptions:
1. Go to Plesk > Subscriptions > example.com > Customize > Resources and set Overuse policy option to Overuse is not allowed, press OK.
2. Repeat it for all locked subscriptions.