I asked about this today, and this was support's answer. Is there a workaround?
I understand that you're seeing an error when trying to connect your client's LinkedIn account. Thank you for reporting this. I can confirm this is an issue on our end. We’ve reported this to our Engineering team, and they’re prioritizing the issue. Please keep in mind that there are many moving parts we need to address before we roll out a solution. We thoroughly test all fixes before they’re released to ensure they don’t affect other Squarespace components or customers. As a result, we can’t guarantee how long it will take to fix issues like the one affecting your site. Also, because of the volume of requests we receive, we can’t always follow up personally when the issue is resolved. That being said, customer bug reports are an important part of how we continue to improve our platform. If you come across any other unusual behavior, please let us know.