Hi all! I thought I had to use microdata tags as well and was losing my mind trying to correct the errors by hand. However, I then set up my catalog through bulk upload with a scheduled feed. In Squarespace, go to Marketing > Facebook Pixel & Ads, and copy that URL. Use that as the data source. Everything uploaded for me nice and neat, no more errors!
These are the articles that sparked my revelation: https://support.squarespace.com/hc/en-us/articles/360001257067 https://support.squarespace.com/hc/en-us/articles/360002041068