Flutter background of unsafe area in SafeArea widget.

Question

Wrap your SafeArea into a widget that adds a background:

Container(
  color: Colors.red,
  child: SafeArea(...),
),

Another way to do it.

import 'package:flutter/services.dart';

Scaffold(
  body: AnnotatedRegion<SystemUiOverlayStyle>(
    value: SystemUiOverlayStyle.light.copyWith(
      statusBarColor: Theme.of(context).primaryColor
    ),
    child: SafeArea(
      child: Container(...),
    ),
  ),
)