Thanks for the report, filed an investigation here: https://bugs.webkit.org/show_bug.cgi?id=253063 You may have success with following instructions, replacing Safari with SafariForWebKitDevelopment: https://apple.stackexchange.com/questions/429814/how-do-you-programmatically-enable-the-develop-menu-in-safari-15-on-macos-12 Unfortunately at the moment I do not immediately have an environment to reproduce the problem here.

Thank you for the report. If you belive it is a Safari issue, best approach would be to file a feedback report, see https://developer.apple.com/bug-reporting/. A runnable example that demonstrates the issue would be the most helpful.

The polygon shredder redux, Cheron particles likely are rendering to 32-bit floats or filtering float textures. Rendering to 32-bit float texture is currently not supported on any iOS device. Texture filtering of 32-bit float textures is currently not supported on any iOS device. On 15.3, EXT_float_blend and EXT_color_buffer_float were incorrectly advertised. This bug was fixed in 15.4. The application should use https://www.khronos.org/registry/webgl/extensions/EXT_color_buffer_half_float/ for both, and work with half-floats on if the 32-bit float extensions are not available. For hevc video missing transparency, please file a feedback request against Safari at https://developer.apple.com/bug-reporting/ with preferably minimal reproduction testcase. You can also post a link to the reproduction case here

Thank you for the report. This is an unfortunate side-effect of some security mitigations. We are working on minimising this regression on future releases. For the time being, to work around you could try if transforming the loops in the GLSL shaders to manually inlined variants would help. Example for (int i = 0; i < 3; ++i) { g1VC[i] = IStoVC(texPos[i]); } -> g1VC[0] = IStoVC(texPos[0]); g1VC[1] = IStoVC(texPos[1]); g1VC[1] = IStoVC(texPos[2]); If you do find a set of loops that manual inlining fixes, we would be very interested in getting the feedback on which ones they are, so we could target fixing the pattern your application uses.

Typo on the last line: should read g1VC[2] = IStoVC(texPos[2]);