http://samanna.net/gen.info/buffs.shtml
This has a "level limit" for buffs table on it. It appears to be level dependent.
I don't see a consistent formula for it, though, we're only up to level 65 (70?) on PEQ, so implementing it for even the lower levels would help. Of course, it would need a rule value determining if you want to enable this per-serverop.