How to highlight Label instead of invalid feedback div - forms

Question

I'm facing a problem with bootstrap 4 form validation feedback error. I'd like to have the label to change color instead of the invalid-feedback div to appear under the input field. Please how can I achieve my goal? Below there's the form I'm using and boostrap version is 4.5.
Thanks a lot for any help you can give me.
enter code here
<div class="row">
<div class="col-md-12"><!--Grid column-->
<div class="myeditform">
<form action="page.asp" id="add-form" class="add-form" method="post" novalidate>
<input type="hidden" id="action" name="action" value="addnew">
<div class="row">
<div class="col-md-8">
<div class="md-form mb-0">
<label for="ev_title">Title *</label>
<input type="text" class="form-control" name="ev_title" id="ev_title" placeholder="Title ..." required="required">
<div class="invalid-feedback">This field is required</div>
</div>
</div>
<div class="col-md-4">
<div class="md-form mb-0">
<label for="ev_is_active">Status</label>
<select class="browser-default form-control" id="ev_is_active" name="ev_is_active">
<option value="true">ON LINE</option>
<option value="false">OFF LINE</option>
</select>
</div>
</div>
</div><!-- row -->
<div class="row">
<div class="col-md-6">
<div class="md-form mb-0">
<label for="ev_at_place">Location *</label>
<input type="text" class="form-control" name="ev_at_place" id="ev_at_place" placeholder="Location ..." required="required">
<div class="invalid-feedback">This field is required</div>
</div>
</div>
<div class="col-md-3">
<div class="md-form mb-0">
<label for="ev_dance_type">Evening of *</label>
<select class="browser-default form-control" id="ev_dance_type" name="ev_dance_type" required="required">
<option value="">Seleziona...</option>
<option value="op1">op1</option>
<option value="op2">op2</option>
<option value="op3">op3</option>
<option value="op4">op4</option>
<option value="op5">op5</option>
<option value="op6">op6</option>
<option value="other">other</option>
</select>
<div class="invalid-feedback">This field is required</div>
</div>
</div>
<div class="col-md-3">
<div class="md-form mb-0">
<label for="ev_cycle">Frequency *</label>
<select class="browser-default form-control" id="ev_cycle" name="ev_cycle" required="required">
<option value="">Seleziona...</option>
<option value="7">7</option>
<option value="14">14</option>
<option value="21">21</option>
<option value="28">28</option>
<option value="0">One time off</option>
</select>
<div class="invalid-feedback">This field is required</div>
</div>
</div>
</div><!-- row -->
<div class="row">
<div class="col-md-12">
<div class="md-form mb-0">
<label for="ev_description">Description *</label>
<textarea class="form-control" name="ev_description" id="ev_description" rows="10" placeholder="Description required ..." required="required"></textarea>
<script>
CKEDITOR.replace( 'ev_description');
</script>
<div class="invalid-feedback">This field is required</div>
</div>
</div>
</div><!-- row -->
<div class="row">
<div class="col-md-12">
<div class="md-form mb-0">
<label for="ev_notes">Note</label>
<input type="text" class="form-control" name="ev_notes" id="ev_notes" placeholder="Es. ...">
</div>
</div>
</div><!-- row -->
<div class="row">
<div class="col-md-12">
<div class="md-form mb-0">
<button type="button" class="btn btn-primary mybtn float-left" onclick="history.go(-1)">Back</button>
<button type="reset" class="btn btn-warning mybtn float-left">Reset</button>
<button type="submit" class="btn btn-primary float-right" >Add</button>
</div>
</div>
</div><!-- row -->
</form>
</div> <!--myedit form-->
</div><!--Grid column-->