The Timeout option use "regular" timers, same as system use for its timeouts, e.g. of notifications, network connect/read timeouts, etc., those aren't very accurate, especially if the app is "power save" throttled, or the device goes to sleep.
I'm hesitant to rework such timeouts, e.g. in the Notification action block, to rely on the "Timer accuracy workaround" option (see setting), since there's may other system APIs i would be unable to apply it to anyway.
But i'll update the documentation with a notice of the inaccuracy.