I’ve heard back from our engineers and they’ve let me know that it looks like one of your columns that is being mapped to a single select field is causing this error. There are some limitations where you can only have 200 options within a single select field, and all those options combined can only be up to 150,000 characters. It sounds like it might be a column accidentally being mapped rather than intentionally.
Are you able to take a look and see if any of your columns are being mapped as a single select field that should be?