I noticed this is not on your list of known bugs in the latest steam post, however this is severely game breaking especially using an artificially high ping.

In short you are able to take multiple skill nodes by clicking fast enough for it not to register, making you use skill points you do not have.
This in itself is not an issue, however seeing as you can confirm the skills you could get all skill points at level 2.

The cause is high ping

The fix is easy though, just make people unable to confirm if they have allocated more skill points than they have.

Videos:

Spam clicking the same node uses multiple skill points for one skill:
https://youtu.be/iABmDoZVWTM

Clicking multiple nodes grants you all skills clicked:

https://youtu.be/8FkB8_ddMTs