@christophe-leborgne it seems that you are going around a circle here!
Please find a different iPhone and set it up there. If it doesn’t freeze then it’s you phone.
You have been given quite few options to try and you haven’t mentioned if you have attempted any at all.
To be fair this issue with Suunto app freezing is unheard of. I have m never seen the app misbehave which leads me to believe that you phone is most likely the culprit.
Again, your best bet is to try with another iPhone.