How to reproduce:
1. Open the attached "1299541.zip" project
2. Open "Test" Scene and select the "Timeline" Object in the Hierarchy
3. Go to the Timeline window and set the frame to 70
4. Press the Record button for the "Cube (Animator)"
5. In the Scene View move the Cube around
6. Stop the recording
7. Double-click on the "Recorded" track

Expected results: The Animation key is created in the same frame as in Timeline (frame 70)
Actual results: The Animation key is created in a different frame (frame 69)

Reproducible with: 1.2.6 - 1.4.3 (2018.4.30f1, 2019.4.17f1, 2020.1.17f1, 2020.2.1f1, 2021.1.0b1)
Not reproducible with: 1.4.4 - 1.4.5, 1.5.1-pre.3 (2019.4.17f1, 2020.1.17f1, 2020.2.1f1, 2021.1.0b1)

Note:
- Changing the desired frame from 70 to a different one and then back to 70 "fixes" the issue
- Only appears to happen with frame 70
- Would be advisable to delete and re-add the Project after each reproduction attempt, since it might not reproduce after changing the Project version
- 2018.4 stream doesn't have Timeline as a Package, thus doesn't have different versions