lightroom collapsed when sincronising photos

Some possibilities

1. In LrC /preference/performance/ do you have the Use Graphics Processor turned on? If so, try with it turned off. If that works, a GPU driver issue might exist.

Incidentally, in LrC, in Help, click on System Information. What is reported for the GPU??

example:

Graphics Processor Info: 
DirectX: NVIDIA GeForce RTX 3070 (31.0.15.4601)
Init State: GPU for Export supported by default
User Preference: Auto

2. Sometimes buggy behaviour by LrC indicates that the preference file got corrupted. Have you considered resetting it?

https://helpx.adobe.com/lightroom-classic/help/setting-preferences-lightroom.html

https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/

3. In this community, if you search on say "settings paste crash" you will find several postings similar, the above two possibilities are reflected in some of those. You can look at them for additional ideas.

Sync?

Sync to/from where?