wc-ajax pending on checout page

Hello there!

We have a question about some weird plugin behaviour on our website.
When the plugin is enabled (disabled right now), on the checkout page, when the PayPal payment method is selected, on the checkout button clicked https://prnt.sc/16vfoVu4YD8S, customers have to wait a lot of time (more than one minute) to be redirected to PayPal system page.
?wc-ajax=checkout has a long-pending time on the network tab https://prnt.sc/enkguGr54I6M.

As the result – clients can’t wait for so long, and we have a lot of orders in pending payment status (which appears as cancelled after some time).

When cleverreach plugin is disabled, everything works fine.

Any ideas, on why it could happen?
And how we can fix it?

Thanks in advance!

The page I need help with: [log in to see the link]