I dont know what happened exactly because the problem is there for some time now but i have been ignoring it because i use google-chrome mainly. Firefox used to open showing a black frame. i think i saw a segmentation fault when i tried to open the application from the console. So i did a clean reinstallation and nothing really changed. the error i can see is
[88314, Main Thread] WARNING: failed to open shm: Function not implemented: file /builddir/build/BUILD/firefox-70.0/ipc/chromium/src/base/shared_memory_posix.cc, line 250
zsh: segmentation fault (core dumped) /usr/bin/firefox
The current installed version is 70.0