too many redirects- how to diagnose this?

too many redirects- diagnose this

I have some unusual behaviour with a wordpress page and the redirects – and i need some advices. Well – i am not sure what exactly is happening.
At the moment i cannot mention the real domain here in public as the project is under development.
In my own chrome developer tools I see a direct 200 success. Some but not all other users report a “too many redirects” error.

Question now is what is the best way to diagnose this?

some reporting users recommend mobile app browsers, so no dev tools I could ask them.

Background: i don’t use any special htaccess rules, and also no WordPress plugin I’m aware of doing redirects.

But – i use some of the plugins. How to test – if it is a plugin that is responsible for the error…

This can be done, for example, with an external tool like https://httpstatus.io/

httpstatus.io: here – we ought to just enter the URL we want to start with.
Afterwards we see the result and then show us whether the page could be opened directly with a 2xx code, or whether there are one or more redirects (301) in between.

Well this is a very interesting approach:

What do you mean!?