My site is having this issue as well. It's been weeks and Google Site Console is specifically showing the error about there being duplicate content. I've tried adding canonical tags and redirects to no effect.
If I cannot resolve this issue soon, I will be forced to cancel my Squarespace subscription, request a refund, and re-create my site with another service.
I'm very disappointed that this issue has been known for years. The positive marketing about Squarespace is not backed up by my experience with this hugely important aspect of websites (that Google can find them).