For Debian 11 run the following:
Keep in mind that the owner of the key may distribute updates, packages and repositories that your system will trust (more information).
echo 'deb http://download.opensuse.org/repositories/home:/frederic-loui:/p4lang:/p4c:/main:/debian11/Debian_11/ /' | sudo tee /etc/apt/sources.list.d/home:frederic-loui:p4lang:p4c:main:debian11.list
curl -fsSL https://download.opensuse.org/repositories/home:frederic-loui:p4lang:p4c:main:debian11/Debian_11/Release.key | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/home_frederic-loui_p4lang_p4c_main_debian11.gpg > /dev/null
sudo apt update
sudo apt install obs-service-recompress