World content that scales with ilvl has been bugged like this for as long as I can remember, because the game sort of lies about the damage you’re doing.
E.g. for my mage, the target dummies in elysian hold are scaled up to 1.46M health from my ilvl, but really only have their base 1179100 health. My arcane orb says it does 4101 damage when it hits, but really only does 4101*(1179100/1460000), or about 3311 damage to the target dummy’s actual health bar, and TotM damage is computed based on that, effectively only doing about 30.3% instead of the expected 37.6%. I believe all “based on x% damage done” things like leech and other abilities have been bugged in open world content like this for as long as ilvl scaling has been a thing.
It’s always been fine in relevant instances (e.g. I got the appropriate TotM damage when I hopped into M spires to test rq) before now. The issue in fated raids was much more extreme, so I’m not sure if they just really messed with real HP values or if it was some new issue entirely.
tl;dr: It’s definitely still bugged in outdoor content to the same degree it always has been, but it seems to be working fine in raids from logs I’ve seen post-fix.