I think everyone can agree, smartphones can feel like a trap device at times.
If you're like me, you have everything on your phone. That means you need to check your device for your work, and can end up in you losing time doing something unrelated.
Good thing: iPhones have a great feature that can help you with that.
Screen in Black and white
Just by clicking three times on your on/off button, you can put your screen in black and white only. With no colors on your screen, you can't forget that you're in focused mode right now.
Go in setting>Accessibility>Accessibility Shortcut>Color Filter
Next time you're working, triple click on the button to not get trapped again.