There is a new pull request by emacsomancer against master on the void-packages repository

https://github.com/emacsomancer/void-packages picom8.1
https://github.com/void-linux/void-packages/pull/24762

picom: update to 8.1
- Fixed #470 #471 #474 #465
- Worked around #301
- Fixed specifying a window id with the picom-trans script
- Fixed minor memory leaks 

https://github.com/yshui/picom/releases/tag/v8.1

A patch file from https://github.com/void-linux/void-packages/pull/24762.patch is attached