I'm running AEX's latest version: 25.3.0 (Build 52), and AMD 5900X and RTX 3080 on Windows 11. The comp is 60 fps & 4096×2160. The animation starts at -80° and ends at -35°, and lasts 2.5s, though the bug appears regardless of duration and composition frame-rate. This is a very odd bug as the animation should be smooth (as it is when you just play with the slider in the effects panel), though it appears very stutter-y.
This is not a performance issue, as my timeline is fully cached and plays at 60 fps real-time. After Effects just seems to be unable to animate the direction of the drop shadow in increments less than 6°. Rendering does not help either, as you can see in the attached footage.
You can easily recreate this by applying a drop shadow on a layer and try keyframing the direction of said shadow.