Sorry if I am not posting in the right format.
I can replicate this issue.
Using Ubuntu 22.10 and Nextcloud client 3.6.6
If Nextcloud client is running and I try to rename (using the Files program) a file that is being sync’d by Nextcloud and that filename has asterisks in it, then the Files program immediately closes/crashes.
If I close the Nextcloud client, I can use the Files program to rename the files and take out the asterisks. Then restart NC and it will sync.
This could be an Ubuntu/Files issue or a Nextcloud issue.