Reproduction steps:
1. Open the attached project ("case_1216698-W_G_Animation.zip")
2. Open the repro scene ("AnimationTest")
3. Select "Wallace_12CYT_Sht09 - No Offset" GameObject in the Hierarchy
4. Open its Timeline and go to frame 38
5. Notice the teeth popping out of the actor's tongue
6. Rollback the timeline a few frames back and press play to play the timeline
7. Notice that the artifacts aren't appearing

Expected result: Timeline scrubbing matches playing (stepped) animation
Actual result: Timeline scrubbing does not match playing (stepped) animation (some artifacts can be seen)

Reproduces on: 2019.3.3f1, 2020.1.0b1, 2020.2.0a2
Couldn't test with 2017.4, 2018.4 (Timeline package not supported)

Notes:
1. Applying half-frame (or smaller) offset to the animation fixes the issue.
2. Artifacts do not appear when the timeline is played