I figured why Gmail login doesn’t work on iPhone and how to correct the issue on iPhone. I hope this is a universal fix for all iOS devices!

Kindly follow the below steps:-

  1. Go to Settings and safari
  2. Open Advanced at the bottom of the list
  3. Experimental Features
  4. requestIdleCallback (it’s at the bottom of the experimental features list). Uncheck (move the button from green to gray or ‘off’)
  5. Restart your device/iPhone and you should be good to go.
  6. Launch Safari and try to log in to Gmail.