Itâs not a bug. Itâs server delay to response times.
So itâs kind of random. ToD is off GCD so technically you can ToD a target in threshold instantly, however if health bars fluctuate too fast sometimes the server doesnât register that health percentage properly for ToD to go off.
Itâs tightly related to delay, MS, and servers themselves if ToD feels buggy sometimes and just doesnât work in threshold. This was explained much better by Trill on his stream at some point but I donât remember when it was