A friend and I were playing Factorio [2.1.17] using this mod, in addition to around 100 other mods, and although she had no issues as the host, I consistently desynced whenever I placed or removed a beacon mk2. From what I can tell in reading the fairly barebones desync logs, the client (me) and the server (her) fail a "crc test (heuristic)", resulting in me getting booted as the server keeps going, but this is the only line in the logs that express something tangible about what has happened:
' Error InputActionHandler.cpp:3012: Multiplayer desynchronisation: crc test (heuristic) failed for crcTick(46535070) serverCRC(3552469724) localCRC(450056591) '
Then there's also a few lines about receiving UnparsedNetworkMessage(s), rather than the literal hundreds of such messages I find in my previous desync logs.

I wish I could add more details about this to be more helpful with the debugging, but I don't know where to start with such sparse info in the logs. All I can add for now is that wretlaw120's latest version of "Beacon Rebalance" (from almost 2 years ago at this point) works fine with all the other mods we're using; aside from a fairly innocuous visual bug.

Hope you're able to fix this issue, it's a great mod otherwise :D

Well I have personally zero experience with desync issues and solving them, but I think we(as in the modding community) can figure that out.
Can you send me the modlist on Discord in a PM. Or use the issue I open for that https://codeberg.org/pla/wret-beacon-rebalance2#1
And the file script.dat of the desync report maybe.
And, is this only with the new 2.1.3 version, maybe you could test if it happens with the 2.1.2 version too.

Here is more info where that desync report is https://forums.factorio.com/53851

I hopefully fixed the issue. Last question, did you use Stable Foundation in that save?
Please report back if the issue is really fixed.