You’re completely right.
Anyway, my procedure has been:
- Clear Cookies.
- Reset Device ID (JV generates a new Phone ID, Unique… and you still need to LOG IN so it’s likely fresh)
- Add your custom API UserAgent
- Log In with the acc.
- On IG go to Settings, Security, Login Activity and do ‘It was me’ thing.
After that, everything has been working till now (fingers crossed).