@malte Such a directive is currently not available in MDB5 Angular but I added it to our to-do list. As a workaround for now you can use this custom solution:

HTML:

<mdb-form-control>
  <input mdbInput [formControl]="input" type="text" id="form1" class="form-control" />
  <label mdbLabel class="form-label" for="form1">Example label</label>
</mdb-form-control>
<div>Character count: {{ characterCount }} / {{ maxLength }}</div>

TS:

  input = new FormControl();

  characterCount = 0;
  maxLength = 15;

  constructor() {}

  ngOnInit(): void {
    this.input.valueChanges.subscribe(value => {
      this.characterCount = value.length;
    })
  }

Edit: This implementation is now available in the input documentation: https://mdbootstrap.com/docs/angular/forms/input-fields/#section-character-counter