Got it! Yep, the team recently pushed out HTTP API v2 to solve some issues it had at the time and improve what information it can parse correctly. For example, sometimes a few of the inputs given could have extra quotations in the text and that broke it/caused it to "Failed to parse body". With v2 that shouldn't be an issue and should be easier to troubleshoot your setup.
The only issue is that templates need to be saved again in this new version due to the format updates. You no longer need to give the variable token quotation marks
Your previous templates should still be accessible via any table that still has old versions of this integration like the table above to copy/paste, update the format, and save. I don't think it can do it automatically unless it's given the formula or you map it.