Raindrops will seemingly disappear or change position mid-fall. This does not seem to occur when the tick rate is 0 and is hard to notice with tick rate 3+, so the easiest way to repro is to run /weather rain
and /tick rate 1
and watch the rain for a while. (Do not move your player while doing so to avoid triggering the related MC-187442.)
For a video, please see
[media].
Can confirm 1.20.2