Current workaround is as follow
- Open Thunar
- Go to Edit > Preferences…
- On Display tab, check or uncheck Show file size in binary format at least one time (and choose what you like before you press close)
We can see the update on fix at the following location
Thunar 1.64, 1.65, & 1.66 crash when moving files – https://bugzilla.xfce.org/show_bug.cgi?id=11450