Thank you for reaching out!
I understand that on all four sites, Square payment method fields won’t load at the checkout page.
This isn’t something we were able to replicate on our test sites.
There’s a known compatibility issue with Divi theme and a few different plugins.
This happens when the Autogenerate descriptions option is enabled in All in One SEO Pack plugin:
https://cld.wthms.co/RDKhfB
And as @simplepicturehanging mentioned, plugins like Litespeed Cache are also capable of causing this.
A plugin/theme conflict test will help you determine which plugin (or theme) is causing this behaviour:
https://docs.woocommerce.com/document/how-to-test-for-conflicts/
I’m not aware which exact JavaScript files need to be excluded in the settings of Litespeed Cache plugin since I’m not familiar with how exactly this plugin works and each case might be different, but you may want to try excluding all JavaScript files found in the Square plugin folder.
You may also want to reach out to the support team of Litespeed Cache for assistance with the configuration of this plugin.
I hope this helps!