It can be literally any reason behind the crashes happening on your particular Rig as every build is different so it is hard to say what is causing em.
BUT, I strongly believe that the core reason behind majority of CTDs for this game is related to Shader Cache files.
Now there are two main reason why I say this,
One, is because I tested a workaround suggested by someone on this thread to basically delete the Shader folders located under Documents.
I did exactly as instructed and now crashes are completely gone for me. At least for now and until another patch comes out and messes up the files again.
Second, is because the Devs themselves in the official patch notes for Tu8.5, listed a fix they had planned to deploy to fix crashes which is related Shader files also.
Here's what the notes say, "Fixing an issue causing graphic issues and crashes on PC due to corrupted shader cache files."