[Garkin]

Originally Posted by Sasky local d_old = d d = function(...) end zo_callLater(function() d = d_old end, 2000)

It is not a good idea to restore function from backup, because you never know if any other addon hooks the same function after your addon is loaded.
Method used by thelegendaryof's BugEater is better.

local ignore = true
ZO_PreHook("d", function() return ignore end)
 
EVENT_MANAGER:RegisterForEvent("Debug_Hook", EVENT_PLAYER_ACTIVATED,
   function(event)
      zo_callLater(function() ignore = false end, 250)
      EVENT_MANAGER:UnregisterForEvent("Debug_Hook", event)
   end)

EDIT:
I have to say that instead of hooking d(), it is better to use code provided by Fathis Ules. It works even if addon uses different method of displaying of chat "spam":

EVENT_MANAGER:RegisterForEvent("Clear_Chat", EVENT_PLAYER_ACTIVATED,
   function(event)
      zo_callLater(
         function()      
            for i = 1, #ZO_ChatWindow.container.windows do
               if _G["ZO_ChatWindowTemplate"..i.."Buffer"] then _G["ZO_ChatWindowTemplate"..i.."Buffer"]:Clear() end
             end
         end, 250)
      EVENT_MANAGER:UnregisterForEvent("Clear_Chat", event)
    end)