As a general rule, no. However, there have been cases where switching a site to CloudFlare has seen significant negative SEO impact, presumably because of what is often referred to as "bad neighbors" or IP tainting. Basically, someone with poor/unlisted content sharing an IP address with the site in question. There is no way to tell for sure. Then again, I am not convinced there will be any benefit for having CloudFlare in front of SquareSpace domain either. Might not be worth the hassle.