Then template limit is ignored/set to unlimited. A more or less similar problem with database was mentioned here in 2016 Will this be fixed? Please exclude -1 and 0 for all quotas for normal users or refer to the template limit.
A user can not set quota to -1 (unlimited), just tested. But he can set it to 0 at the moment which then gets interpreted by the Linux quota command as unlimited and not as 0. I will exclude 0 as value completely as neither client nor admin should be able to set it to 0.
