I have a .Net Core MVC project with HTML Bootstrap 4.8 and JS.

Some user requests takes longer (like 30 seconds or even more) due to the nature of my business. These are async AJAX requests, and while this happens I do show an animated icon/block at screen. But if user press esc then this icon is removed and user can browse freely again (this also happens if user works in another browser tab).

I was considering to make them async: false so this would make browser unresponsive while waiting for the return. But this is deprecated.

An alternative approach would be to create a backend strategy to hold while that request is being evaluated.

What should I consider?