blue box appearing after consent

@markagregory thank you for your report. Was the module installed before and updated or a fresh installation?
I don't really think this is a bug in the module, more precise I think it's a custom issue on your side (theme or whatever), but let's see.

What's the HTML content / classes of that box?

The steps were:
1. installed Drupal 10.1.5
2. installed gavias-winnex theme that includes a builder
3. installed cookies - placed the custom block into the footer

If you go to the website mentioned in the steps to reproduce you can select accept all and see the box appear. Possibly this will help identify the problem.

Thanks @markagregory

It's the Drupal message area appearing:
<div class="" data-drupal-messages=""><div class="messages__wrapper"></div></div>

COOKIES is making an AJAX call and it looks like any module or theme is acting on that (probably JS attach handling the ajax content or whatever) and adding that box.

I'd suggest to retry with a different theme. If it still appears, try switching off modules, that may cause this in a copy. I never saw that issue before and COOKiES doesn't add messages on that callback.

We can't offer further unpaid support, sorry. I'm 99,999999% sure this isn't a COOKiES issue. Please reopen with details how to reproduce this in a vanilla Drupal installation. If I'm wrong, of course we'll then help fixing it.