One Of The Oddities With Squarespace (There Are A Few) Is How It Handles Canonical URLs - Spoiler Alert - it's too easy to create duplicate content.
A canonical URL is a fancy term for the default or preferred one you wish to use. Overgeneralizing here, the consideration typically includes using www.yoursite.com OR yoursite.com. With or without the www. I’m assuming that your URLs are already SSL (start with HTTPS) - if you’re not there yet - just do it.
Once you decide on which canonical to use - be extra careful on Squarespace of how you end your URL. https://thispage.com and the same URL with a trailing slash https://thispage.com/ are NOT always treated the same and could create duplicate-content issues for you which are not likely to trigger a warning in Google Search Console.
Grooming is fairly easy but certainly is time-consuming for larger sites. Either use an audit tool to report all your page-level links as well as internal & external links and make sure they follow the intended format. For Squarespace, make sure your links all end without the trailing slash - Squarespace will add the trailing slash when the link is visible. Go ahead, read again.
PRO-TIP: Google sees some URLs as unique and separate pages if you're applying the trailing slash incorrectly - see what their John Mueller had to say about it in this Search Engine Roundtable post.
A bump in the number of indexed pages usually follows this exercise, which puts more of what you've got out there to be discovered.
Try it and let me know how it worked for you!
BTW, these tips also work for other website platforms, but Squarespace creates more of a mess with these issues than other platforms.