After having the same issue I reached out to Squarespace support and received the following workarounds:

1. If you use the www version of a link, such as www.yourlink.com vs. yourlink.com, it will prevent the parameters from being stripped.

2. Another option would be to use "#" instead a "?" when creating the utm tracking.

We implemented #1, and it's been working seamlessly. Hope this helps!

After having the same issue I reached out to Squarespace support and received the following workarounds:

1. If you use the www version of a link, such as www.yourlink.com vs. yourlink.com, it will prevent the parameters from being stripped.

2. Another option would be to use # instead a ? when creating the utm tracking.

We implemented #1, and it's been working seamlessly.