I can confirm that one of my plugin also has a rendering issue on macOS Sonoma (Intel chip). The level meter is not able to render smoothly (should be 60Hz, trigger by a Timer) and eats much more GPU than before (source code is available here, a little mess 
).
- this plugin renders smoothly on Win10 virtual machine on the same MacBook Pro
- another plugin which renders an oscilloscope (by OpenGL) still works properly