After enabling chat message signing my server has started to randomly get "Chat validation error"s which happened for no apparent reason. All of the sudden everyone on the server will be unable to chat, when players try to chat it says "Chat validation error" in red and then a few seconds later lots of players get kicked from the server. The message shown to players when they get kicked is "Received chat packets with missing or invalid signature."

There is no info in the logs about these chat validation errors whatsoever. There are no errors in the logs when this is happening.

The server will go hours without this happening, then all at once it will happen up to 3 times in a row in just a few minutes.

Lots of others have created tickets about this, but those tickets were closed because "the server is modded" but this appears to be a Minecraft bug with chat signing. If you don't fix it then servers are just going to keep chat signing disabled. If you want servers to enable chat signing then you should fix this bug. It's happens for no apparent reason so you should stop telling server owners to try and reproduce it with vanilla.