The timers for timing keys as +1, +2, +3 no longer seem to be accurate. Was in a key where the timer was saying we were in the +1 range for a little while but it ended up being +2 from Blizzard's frame as well as RIO.

There was a patch on October 29th that added an extra 90 second timer to the Challenger Peril's affix (for keys 7+) so maybe that is what is causing shifting of the end times? https://us.forums.blizzard.com/en/wow/t/mythic-affix-change-incoming-october-29/1995944

I can't fully tell if the total timed completion (meaning +1 max limit) is accurate or not since I can't see both timers at the same time but I can confirm the +2 and +3 seem off for sure at least.