https://github.com/RecursiveG/Mc122477Fix and https://modrinth.com/mod/mc122477fix-updated come close to fitting the bill, but aren't exactly it. Linux and some mac users are affected by this (double key for chat open) and is frustrating that there isn't a forge mod to fix it

I can look into it. The workaround I've used for years is adding XMODIFIERS="@im=null" to /etc/environment. No idea what the equivalent is for Macs though, and this workaround probably doesn't work on Wayland either.

IIRC, Sodium/Embeddium also include a fix for this bug.