Login redirection issues

Hi. I have recently made and started using my own plugin, which rewrites all URL’s in my page to have a language prefix in front of them.

But I noticed an issue, that seems to happen only with Theme My Login plugin: when login page is using lang prefix (i.e. https://www.page.com/en/login/) and when there is some login error (lets say user is not found), the error message is not displayed and url of page after trying to log in changes to:
www.page.com/en/login/?action=failed&username=tester&redirect_to=http%3A%2F%2Fwww.page.com%2Fwp-admin%2F

Strangely the issue is not appearing when original URL is without prefix: https://www.page.com/login/ – then page is redirected to same location and error is dipslayed.

I am trying to fix this, but I am unable to find out how. Again, this happens only with your plugin (I tried same with Paid Memberships Pro – works). Can you maybe give some hints where the problem might be happening?

Worth mentioning: when debugging, I have disabled my plugins’ redirection. I think there is some problem with how your plugin managed redirections, but I cant find out where exactly.