Since I have an Intel Arc card, my first suspicion was that the updated couatl64_MSFS2024 was somehow incompatible with Arc GPUs
The Couatl engine doesn't have any relationship to anything graphic. It's just a custom Python interpreter, with no graphic libraries, and the one and only connection to the sim is through the standard Simconnect interface. No interaction whatsoever with any graphic systems in the OS.
but then someone on the GSX discord reported exactly the same issue as mine. I asked him what card he had and he replied that it was an RTX 4070.
It's impossible someone with an RTX 4070 could have the "exactly the same issue" you are having, because your crash happens in igd12um64xeh.dll and that's part of the Intel drivers, doesn't exists on other cards so no, the issue he's having is different.
With today's update (3.3.5), Couatl64_MSFS was updated and it also no longer works on my PC. As a consequence, GSX Pro no longer works in MSFS 2020 either and the GSX Pro is now completely unusable for me. This is getting ridiculous...
As I've said, nothing in the Couatl .exe can possibly crash the sim, this is not open to discussion, it just can't.
However, if the problem is related to your graphic driver ( we are not sure it still is, because you haven't provided with an updated Event viewer or said if you saw a crash in Flightsimulator.exe BEFORE the Couatl .exe crash ), it might be very possible that, because of a graphic driver bug, when GSX is creating what is a normally perfectly legal vehicle that works for everybody, since this vehicle has to be drawn by the sim, a graphic driver bug might crash the sim like that, so you can be easily mislead the problem was caused by GSX ( because "it doesn't happen if you remove it" ), but the real cause was some problem or bug that prevented the sim to create a fully working object on behalf of GSX and the graphic driver CAN crash the sim.
The way Simconect works, there's only one way to create objects, and it doesn't involve meddling with graphic at any level, it's just a command sent to the sim that says "please create the object named xxxxx at those coordinates", that's it, it's a black box for us, there's no "wrong" way to do it, if the object is legal according to the SDK ( and it surely is, otherwise the SDK wouldn't even compile it ), if the sim crashes, it's either because it has exhausted all RAM or VRAM, or because there are too many objects already, or if there's some problem in the graphic drivers.
Sometimes, MSFS simply doesn't start after Windows has been running for a very long while and MSFS was started too many times. A Windows restart usually fixes it. Again, nothing that has anything to do with GSX.