I found a way to bypass server chat filter by using an invisible character.

What I expected to happen was...:
I expected for nothing to happen, but soon realized I produced an invisible character.

What actually happened was...:
An invisible character showed up, one which I've never seen before. I tried using this invisible character to bypass chat filter of a server and it succeeded.

Steps to Reproduce:
1. Open chat box

2. Press either F1, F2, F3, and so on

3. Tadaa, your invisible character has now been made

This invisible character to do things like "(F1)/kill @a", but instead of running the command, it displays it in chat.