1. Windows 11 Pro, Version: 21H2, OS Build: 22000.795, Experience: Windows Feature Experience Pack 1000.22000.795.0
2. Start11 Version: 1.24
Image of systray before reboot, specifically the Advanced System Care icon, first icon in systray top left.

Image of systray after reboot, notice ASC icon is once again in the hidden icons

This happens with other icons as well, but it is intermittent, however the ASC icon "always" goes back into the hidden icons every time I reboot.