Https to http redirect is not happening in safari latest version

I am using http website and when a user click on submit button i authenticate using 3rd part url which is https.

Http to https redirects happening fine, and after successful authendication 3rd party website return response with authorization details back to my http website. Here is the problem, i am getting "this form is not secure, are you sure you want to submit it" in iPhone and iPad and in mac safari i am getting "this form will be sent in a way that is not secure are you sure you want to send it".

I tried with iPad with iOS 9.3.5 safari and mac Safari 11.1..2 and after confirming the above security warning i am able to proceed with post authorization process, but with iOS 11.3 and above safari is not really loading the page but forever loading on the same page.

I added my website as top site and no luck. I just want to know whether it is possible to add any kind of exception to allow my http website so that https to http redirect is possible. If it is not, possible please let me know the fix.

Thanks,

Pravin