So I didnt play here since Outland server but is that some kind of new anti afk mechanic that our toons get inactive debuff despite dealing damage on players when its not your main window? Its not consistent so I suppose it relies on player reporting and it happend maybe 5 out of 100 bgs now but especially when defending alterac towers that one of my toons gets booted from the BG with inactivity debuff even when there is pvp fighting going on. Maybe some of the long term wotlk players have more insight on how this works here.
There are two debuffs: "Idle" (the one with the closed eye) is triggered by player reports. After one minute as "Idle" you become "Inactive" (the one with the cow)
If you are seeing the "Inactive" debuff (the one with the cow) directly without having been "Idle" (the one with the closed eye) first, then you are flagged by the automatic afk system.
Like a year ago they changed the anti afk warden to act super aggressive.
Sometimes one of my toons dies at the start of a encounter and he gets kicked from the BG while I'm still fighting with my team.
On wotlk inactive debuff gets removed when you deal dmg or heal. If that's not the case for you then it might be a TBC related bug.
As far as I know they changed the anti afk warden during the AV bridge farm meta back on Onyxia because ppl had the habit to go afk and leech HKs there.
For some reason they never fixed the warden to act normal since then.