Ionic 5 angular navigation: ion-back-button not visible

Hello! I’m posting here a question I posted on stackoverflow. Some people posted possible solutions but I would like to know if there is a “more official” way to solve this problem.

i have an app with a structure similar to the one I created on this stackblitz. the app have this three routes:

/tabs/tab1

/tab/tab2

/tab/tab2/subtab

I cannot understand If I’m missing something or if this is the navigation system, but when i go from /tab/tab2 to /tab/tab2/subpage I can see the back button. When I go from /tabs/tab1 to /tab/tab2/subpage it is not visible. Is it normal? I would like to see a back button to come back to /tab/tab1 .
Thanks for your time.