Hello, it happens because of display: flex in this element. See class d-flex here:

<div class="d-flex flex-row align-items-center mb-4">
                    <i class="fas fa-user fa-lg me-3 fa-fw"></i>
                    <div class="form-outline flex-fill mb-0">
                      <input type="text" id="fullname" name="fullname" class="form-control" required/>
                      <label class="form-label" for="fullname">Full Name</label>
                      <div class="invalid-feedback">Please type your full name</div>
                    </div>
                  </div>

Try positioning it with our Grid system: https://mdbootstrap.com/docs/standard/layout/grid/