Can't save proxy password anymore (starting by: moz-proxy://)

## Steps to reproduce
Use Firefox 88
### Expected behavior
Save and reuse automatly Proxy User/Password
### Actual behavior
Asking User/Password even when save and reuse tick is on
### Device & build information
* Device: VM+Win10
* Build version: 88.0.1 32bits
### Notes
Attachments: 
