Linear interpolation occurs on constant tangent curve partially

When using UV scrolling for a flipbook-like animation in Animation Sequence, creating keys with "Constant Tangent" settings on Curve Editor does not result in an instantaneous change to the specified value. Instead, unwanted interpolation occurs.

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1. Download the repro project from the attachment.
2. Unzip and open the project.
3. Double-click All > Content > UVScroll > SK_UVScroll_Test_anim asset.

Expected Result:

The UV animation is controlled by the "Offset_U" curve. All keys of this curve are set to Constant Tangent, so the output should always be either 0, 1, 2, or 3 at any given frame.

The material is set up to display the corresponding number on a mesh, so the animation preview should show a flipbook-like effect, changing instantly between frames like 1 → 2 → 3 → 4 without interpolation.

Actual Result:

Interpolated frames are observed, causing a horizontal texture scroll animation instead of a discrete flipbook-like change.