Interpolation of ridden entities is extremely choppy

Partner Rank:
1

Partner Team Reporting:
Everbloom Games

Verification builds:
1.21.10.20_rc0

Summary:
Interpolation of ridden entities is extremely choppy

Impact:

This makes minecart rides or cutscenes that teleport entities that the player is riding look broken and unprofessional. This makes rides in our park maps (Universal Studios Experience, WDW Magic Kingdom Adventure, Haunted Park, Dragon Park) nauseating. Provides a severely poor experience in IP content.

Repro Steps:

1. Open the provided world
2. Head to the white-floored chunk with cobblestone walls and a moving minecart
3. Sit in the minecart and look around

Observed Results:

The movement of the minecart, and therefore the camera, appears to stutter while riding the minecart.

Expected Results:

The movement of the minecart and the camera are both smooth and synced with each other.

Regression Build:

Worked in 1.21.0.26_rc0, doesn't work in 1.21.10.20_rc0

Screenshots / Videos Attached:

Yes. Attached the behavior in 1.21.0, in 1.21.10, and a bonus video recorded using a fixed camera.

Notes:

Also affects vanilla gameplay, to a smaller extent: Minecart rides, and horses. Boats are not affected, surprisingly.