Screenshot timeline thumbnails show a thin line above the frame number on some thumbnails but not others

Steps to reproduce:

1. Create a new 3D URP project via Unity Hub
2. Open the Profiler (Window > Analysis > Profiler) with the Screenshots module shown, Game View open
3. Enter Play mode and record for a few seconds so a run of screenshots is captured
4. Open the Screenshots module details strip (the horizontal thumbnail filmstrip along the bottom)
5. Look across adjacent thumbnails at the seam between the bottom of the image and the frame-number label

Actual results: Some thumbnails show a thin horizontal line between the bottom of the screenshot image and the frame number (e.g. present on one thumbnail but absent on the adjacent one) even though the thumbnails are otherwise identical. Whether the line appears is inconsistent from one thumbnail to the next.

Expected results: The image/label seam renders consistently across all thumbnails - the line shows on all of them or on none.

Reproducible with versions: 6000.6.1f1, 6000.7.0b1, 7000.0.0a1

Can't test with versions: 6000.0.84f1, 6000.3.24f1

Tested on (OS): Windows 11