My apologies if this is just my problem, but the XP download page which sounds like it would offer an outdated version of Avast that still runs on XP seems to be broken: https://www.avast.com/windows-xp-antivirus The download from there just doesn’t actually run on XP and instead complains that a newer Windows is needed. I understand if you don’t want to offer an old version for XP anymore, but in that case maybe that page should be removed since it seems to misleadingly suggest you still offer that.
Assume you are aware of this thread: https://forum.avast.com/index.php?topic=220639.0
Even with v18 Free installed, there is a licence expired tray warning to contend with.
Fair point about Avast still showing link for version for XP.
If you really want to try v18, it is still on filepuma. https://www.filepuma.com/download/avast_free_antivirus_18.5.2342-19226/
What is XP ;D