Authenticated proxys (name:password@proxy) dont save in proxy settings and will have the username:password string removed and just leave the proxy address. I dont know how plasma currently handles proxys but I am currently using gnome which applys proxy settings as an env variable. Plasma proxy even when it works doesnt affect env variables and I think that it would be a good idea to since a lot of applications support it and its useful in terminal. I think this is quite a big issue since it can cause a lot of issues in workplaces that require proxys for network access.

STEPS TO REPRODUCE
1. Open plasma proxy settings
2. Select manual
3. Input a authenticated proxy (username:password@proxy)

OBSERVED RESULT

Proxy will save but once clicked out and gone back into proxy settings it resets to (proxy) instead of (username:password@proxy)

When using an application such as discover it once again proves the authentication is ignored and just shows (proxy) normally being unreachable since the proxy requires authentication.


EXPECTED RESULT

Authenticated proxys to be accepted and also applied to enviromnet variables to use with terminal or other applications that support enviroment variable arguments.


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION

There seems to be another bug with proxys not saving after being saved and being wiped when moving between setting windows. Ill create another bug report for this if it doesnt exist.