Minimum supported OS version is macOS 10.15 Catalina. They should work natively on both M1 and Intel devices. The AppImage should cover any users left on that version. Also Ubuntu 20.04 is dropped from the PPAs because it doesn't have the minimum required Qt5 version (5.15.2).
It is created on Ubuntu 20.04 and it should work on any other similarly aged distro. It uses the latest versions of Qt6, libtorrent, boost, openssl. It will see releases at least until the summer of 2022. The v4.4.x series will probably be the last one that supports Qt5 and therefore Windows 7 and 8. WINDOWS: Users of Windows 10+ can also use the Qt6 version of the installer.