WillPopeScope is now deprecated. I tried using PopScope since your approach isn't working now. Below is the error I'm getting when I try navigating back to the tabs page after setting the meals filter.

[sistercharmings777]

Restarted application in 670ms.
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: 'package:flutter/src/widgets/navigator.dart': Failed assertion: line 5238 pos 12: '!_debugLocked': is not true.
#0 _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:51:61)
#1 _AssertionError._throwNew (dart:core-patch/errors_patch.dart:40:5)
#2 NavigatorState.pop (package:flutter/src/widgets/navigator.dart:5238:12)
#3 _FiltersScreenState.build. (package:meals/screens/filters.dart:43:35)
#4 ModalRoute.onPopInvoked (package:flutter/src/widgets/routes.dart:1574:30)
#5 _RouteEntry.pop (package:flutter/src/widgets/navigator.dart:3083:11)
#6 NavigatorState.pop (package:flutter/src/widgets/navigator.dart:5251:13)
#7 NavigatorState.maybePop (package:flutter/src/widgets/navigator.dart:5204:9)

[jose-guevarra]

Try something like this:

screens/tabs.dart

void _setScreen(String identifier) async {
Navigator.of(context).pop();
if (identifier == 'filters') {
final result = await Navigator.of(context).push<Map<Filter, bool>>(
MaterialPageRoute(
builder: (ctx) => FiltersScreen(currentFilters: _selectedFilters),
),
);
setState(() {
_selectedFilters = result ?? kInitialFilters; // checks if null then
});
}
}

==========

screens/filters.dart

  body: PopScope(
    canPop: false,
    onPopInvokedWithResult: (bool didPop, dynamic result) {
      if (didPop) return;
      Navigator.of(context).pop({
        Filter.glutenFree: _glutenFreeFilterSet,
        Filter.lactoseFree: _lactoseFreeFilterSet,
        Filter.vegetarian: _vegetarianFilterSet,
        Filter.vegan: _veganFilterSet,
      });
    },

==========

for later versions of API(> 34?) you may need to update android/app/src/main/AndroidManifest.xml. Add this to the manifest -> application section

android:enableOnBackInvokedCallback="true"