I've noticed with my flying machine a few different kinds of desync and ejection of my player while the machine is moving. This is best demonstrated with video.

First example is how the machine is intended to operate. This machine operates simply by having two mechanical bearings on either side and rotating 180 degrees on each pivot point to achieve forward flight.

This is very rare to catch on video but I managed to grab it. In this video your player just gets ejected from the seat the instant it is turned into a contraption. Very fatal if you're not prepared for it in one of these bearing machines.

In this next one I added a cabin from one of my other flying machines. I'm not sure what it is about it but it causes you to de-sync incredibly often. When you de-sync your player appears to be at the mechanical bearing but you are actually still in the seat so if you crouch you teleport back. Things like chunk loading and interacting with things still act like you're at the seat so if there are any distance checks they will typically fail. You also exit the seat if you walk far enough away from the mechanical bearing, however you appear where you walked away not at the seat allowing for some strange form of de-sync teleportation.

This last one is what happens when the anchor is loaded but the client can't see it within render distance. It causes this weird double contraption thing and likely tries to place the contraption down several times even though it's already "placed" considering when you're in this state it lags like mad.

Here is the schematic to the cabin I attached to my flying machine:
(It is a text file but just rename it to nbt and it should work.)
flight_cabin.txt

Can confirm this glitch is in 0.4a 1.18.1

This issue has been marked as stale because it has been inactive for 3 weeks. It will be closed if it remains inactive for another 3 weeks.

This issue has been marked as stale because it has been inactive for 3 weeks. It will be closed if it remains inactive for another 3 weeks.

This issue has been closed since it has been inactive for 3 weeks since it was marked as stale.

Also these are the versions I'm running:
Minecraft - 1.16.5
Forge - 36.1.0
Create - 0.3.1c

Also the logs had some interesting print outs, mainly about the point of interest system for villagers freaking out. There were also some warnings when performing the glitch where the anchor is loaded but the client can't see it.
latest.log

Do note: This log is different from the one that would've been logged in the video as I made a brand new instance in multi-mc because my previous mods were making a ruckus in logs when loading the world without them. All the issues I previously mentioned acted the same but seemed to occur slightly less. I'm guessing that this may have to do with the POI system possibly being corrupted after being subject to this for awhile.

I did some more testing and put a bunch of POI blocks on my flying machine and it did not cause the de-sync issue so the POI thing and this are two separate problems.