Hi @luanne, as you are facing this issue, then please create a staging site and share the temporary admin, FTP access.
Also do share a video on how can we recreate the issue on our end.

While sharing the access don’t forget to mark the response as private.

This is not the cPanel link, but PHPmyAdmin https://prnt.sc/0jDh28UmsSo0

Hi, if you are able to access FTP and edit files, then we can arrange a video meeting. I will guide you with the debugging and proceed further.

Let us know if we can arrange this meeting?

Thanks for sharing the access . I disabled all the plugins other than Woocommerce and MultiVendorX on your site and added products from 2 different vendors in the cart . But I did not get any error on checkout .
kindly check the video https://watch.screencastify.com/v/Lfia6aCI1MngKYvGqG9Q
Please make sure this staging site is an exact replica of your live site.

Thanks for informing .
It would be really great if you can give us 5/5 review here: https://wordpress.org/support/plugin/dc-woocommerce-multi-vendor/reviews/#new-post
This would motivate the team further to do their job more efficiently.
Great news! Joining the MultiVendorX community on Facebook (https://www.facebook.com/groups/226246620006065) is a great way to stay up-to-date with the latest updates and get tips from other users. Look forward to connecting with like-minded people and learning more about MultiVendorX.