ikigaiconsulting

This would have been an excellent fix, but Code Injection for some unfathomable reason, was made a premium feature available to only Business and Commerce plans. I agree with the points raised thus far and Squarespace needs to effect a timely remedy.

This is a serious issue. Per the admin's link above, you will get more accurate results by running Chrome Dev Tools locally... it's STILL an issue.
Here are instructions for creating a similar report through your Chrome browser: https://developers.google.com/web/tools/lighthouse#devtools
I'm wondering if anyone has created a template that eliminates the biggest offending scripts from SquareSpace? I would pay for this! Here's a list of the slowest scripts per my report [TIME DELAY]:
use.typekit.net.../ik/vK8u1-ck4….js [2,220 ms] assets.squarespace.com…scripts-compressed/common-fc3e2ea…-min.en-US.js [3,870 ms] assets.squarespace.com…scripts-compressed/commerce-74f3967…-min.en-US.js [2,550 ms] static1.squarespace.com…159…/site.css?&filterFeatures=false [1,880 ms] Total delay from these render-blocking resources = 10.52 seconds

While fast load times are good, their importance is exaggerated. Run any of your top-ranked competitors through Google's Page Speed Insights tool and I bet you'll see they receive poor grades too.
Focus on backlinks, useful content, and building your brand's online presence. It'll help your site far more than anything you can do in regards to speed optimization.

We were noticing the same thing when reviewing the performance of our site. It would be interesting what the Squarespace team's thoughts are. If you can share, it would be great.