The last adjustment to antilag changes are dated from March 17. That build was shipped on TM server on March 19, nearly 7 weeks ago. And apart the collision box issue (sticky chair), I don't see any other changes done recently that could affect players.
Since, according to you, the issue appeared only recently, all I can say is:
this might be related to the box collision issue.
this might be related to the high population of the server, coupled to some other factors (settings, number of people having maxed out levels which might compound the issue, etc.)
this might even be due to external factors (ddos, bad actor sending corrupted data, and such). Since nobody is monitoring server logs atm, it's a possibility (though I guess it's unlikely, but it happened in the past afaik).
We'll know more when TM installs the fixed build. Until then, it is all useless speculation.