I tried removing this plugin from proxy server and it seems that both of these issues are fixed, so i strongly thing this plugin is causing this network-wide issues
For the first issue, you can try it yourself
- Open chat
- Type exactly only "/"
- Now press TAB button
= it will not tabcomplete, it will tabcomplete only if you add any letter after "/" for example try "/m" then press TAB button -- now it will tabcomplete but it will not show all available commands but only commands that start with "m"
For the second issue, you can also try it yourself
- Open chat
- Type exactly only "/"
- Press
Enter to execute this empty command, only slash
= If this does not throw an error, try joining any other subserver you have or try rejoining the server and repeat the process - you'll get error like this (not sure if it's exactly the same for everyone) - https://mclo.gs/DQnjsoT