Amazing mod and could help me a lot :), sadly as soon as the chat is in seperate windows, the resolution in game changes to a really bad one.
Normal:

When opened in seperate window:

What's more it fills like if chat has seperate window it fills like lags xD, No my computer is a monster should have no issues xD

Looks like it was casused by mod FpsReducer-mc1.16.4-1.18 closing