Reproduction steps:
1. Open the attached "UnityStepCurveBugReport.zip" project
2. Open the "BugReport" scene
3. Expand the "StepCurveTest23" Packed Prefab and double-click on the "Take 001" Animation Clip in the Project window
4. Select 23 frame in Animation window
5. Observe the value of Position.y
6. Select 24 frame and repeat step 5
Expected Result: "StepCurveTest23" value of Position.y at 23rd and 24th frame is 1
Actual result: "StepCurveTest23" value of Position.y at 23rd frame is 0
Reproducible with: 2021.1.0a8, 2021.3.21f1, 2022.2.11f1, 2023.1.0b8, 2023.2.0a6
Not reproducible with: 2020.3.46f1, 2021.1.0a7
Reproduced on: macOS Monterey 12.6 (Intel), Windows 10 (by the reporter)
Note: Not reproducible on a new project