We just verified that these crashes are due to eBay finally turning off their old attribute API.
Initially, that move was anticipated for January '22, but it seems eBay delayed it until now. We informed our users about the upcoming change and its incompatibility with GarageSale 7 and 8 in October of 2021:
The solution is to upgrade to GarageSale 9, for which we re-built the internal attribute system to cope with this API change.