Product Review settings changing on their own [27 December 2021]
Product Reviews are being disabled on a daily basis by themselves. Squarespace have acknowledged this issue and reported it to their Engineering team."
If you are using/testing the new Product Reviews feature you may want to regularly check that the feature is still enabled on your site. The Product Reviews feature recently disabled itself on several live sites.
Believed resolved in January 2022 but finally resolved on 4 March 2022.