Jittery and inconsistent shadows

Differing shadow issues on every viewer I have tried. Not even sure how to put into words everything going on. Pixelated shadows, shadows only sharp at certain angles, some shadows disappear at other angles. See videos attached for examples.

Viewers where you can fine-tune shadows (like firestorm) seem to have the same issue, sometimes more exaggerated by certain settings. There is no constant though, one issue could happen on a lower setting and also a higher setting- or not at all. It is incredibly random.

Also possibly related is a texture issue- seeing a seam between heads/bodies. I cannot see the seam on my PC, but I see it on my Mac. Other people on PCs and other versions of Mac chips cannot see it.

To recreate:

1.) Be on a Macbook Pro M4, current version Sequoia 15.4.1

2.) Simply cast shadows anywhere and move your camera

Album with a few videos showcasing issue on both LL Viewer and Firestorm: https://imgur.com/a/sl-shadow-issues-j0QtjoQ

https://secondlife.canny.io/admin/board/bug-reports/p/constant-shadow-issues-on-every-single-viewer-m4-mac

Reproduce the shadow behavior on a MacBook Pro M4 running Sequoia 15.4.1 by casting shadows and moving the camera. Review the attached videos from both the LL Viewer and Firestorm, and compare the reported shadow artifacts and possible head/body texture seam across viewer and hardware configurations. Done means identifying and correcting the rendering issue with consistent shadows across angles and settings.