I wish I had a solid answer for that, I actually made a post about this recently.

Deskflow (synergy upstream) seems to be working well at the moment. Bear in mind they just moved all the repos, but Synergy v2 had a bunch of issues, it was dropped for v3, which is just deskflow packaged up all pretty. Input leap is from the people who were maintaining barrier and forked it a few years ago. Lan-mouse is its own thing, and it works, though its a bit clunky to use.

Right now I'm doing some testing to figure out what I want to use, my concern around barrier is that no updates makes for a security risk, and (for me) it also won't work with Wayland.

With Synergy going back to the open base, I don't really mind throwing them some cash, but its not available yet with Wayland support as a packaged project, so I built it and will be testing more for all of them once I move some things around on my desk to restructure - the whole reason I was looking for something in the first place actually. That won't happen until a free weekend though, so hopefully this weekend, but maybe the following.