[rulezyx]

Seems a bit hardcore to me. Your addon avoids all talking-heads.

So people can't use this function combined with your addon.

No Immersion at all.

I didn't tried anything like that before but it is possible to "fake" max-level and maybe something like this will stop popups.

function GetEffectivePlayerMaxLevel()
  return MAX_PLAYER_LEVEL_TABLE[GetExpansionLevel()];
end
 
function IsLevelAtEffectiveMaxLevel(level)
  return level >= GetEffectivePlayerMaxLevel();
end
 
function IsPlayerAtEffectiveMaxLevel()
  return IsLevelAtEffectiveMaxLevel(UnitLevel("player"));
end

I guess your idea with blocking "forced" shadowlands content is not bad for alts but the current solution seems not user-friendly.