I recently was playing on a multiplayer server and I desynced after hitting q and right clicking on the upgrade planner (or at least that's what I remember doing). The report is available at https://lfcode.ca/upgrade-planner-desync.zip

This desync is super common in all of my games. I've noticed it definitely happens when I press the upgrade planner settings button with an upgrade planner in hand. I can sometimes get it not to happen by laying down a belt, picking it up, and then clicking the settings button with nothing in my hand, but even then it occasionally desyncs.