As in the title, angular-maps doesn't work with Angular 9
The reason is how the viewchild is resolved. If you use ViewChild or ContentChild, angular is updating the way they resolve these queries to give developers more control. You must now specify that change detection should run before results are set. Example: @ViewChild('foo', {static: false}) foo !: ElementRef;.
https://angular.io/guide/static-query-migration