STILL HAPPENING!
Now (moved server over to Linux) :
Left (client) MacOS 12.6 MBP M1
Middle (client) MacOS 12.6 MBP M1
Right (server) Ubuntu 22.04 Ryzen 7 32 GB RAM NVMe SSD, AMD GPU (Radeon)
I don't know if it was Synergy client doing it or not - but I kept getting cases when Linux was the client (on the right) that CTRL, or ALT or SHIFT keys were stuck ON and couldn't be "unstuck" (no sticky keys is NOT enabled in Accessibility) - so I made the Linux box the server - but now I'm getting it jumping back to the Linux machine from the middle MacOS client...