[Yocote]

Thanks for the info! I am not creating my own tooltip though, but adding extra lines to the system "GameTooltip" (and a few related ones), using code similar to this to hook in my code:

local tooltips = {
  GameTooltip,
  ItemRefTooltip,
  ShoppingTooltip1,
  ShoppingTooltip2,
}
 
function events:PLAYER_LOGIN()
  for i=1,#tooltips do
    tooltips[i]:HookScript("OnTooltipSetItem", function(tt)
      MyTooltipAddon:ProcessTip(tt)
    end)
  end
end

What I observe is that my "MyTooltipAddon:ProcessTip" method is no longer being called at all since this patch. The hooking code in the PLAYER_LOGIN event handler is called, and no errors are raised there, but the hooks are just never called, as if HookScript silently no longer does anything anymore.