Hi @giulioaprin
Google Maps depends on this kind of input to improve.
I suggest you provide feedback about the incorrect navigation step using a desktop computer.
This link will explain how to do so.
Cue up directions so the faulty step will show up.
Then select Send feedback which is found at the bottom of the map (not the left panel).
Then click on the flag next to the faulty navigation step.
Then select Problem type. Here you can add some notes.
Use the notes to explain in apparent detail what the problem is. Please specify the exact GPS coordinates where relevant. Also, include deep links to Google Streetview if applicable. The more clear details, the better.
It can take 2-3 weeks before changes show on the map. Google will not notify you about the result. Just check the map once a week or so.
Best of luck
Morten