Black squares on checkbox fontawesome

I'm getting this weird behaviour when using fontawesome:

Simply by adding <input type="checkbox"> on my page, this 2 black squares shows up... I don't know if this helps, but the generated HTML is this one

<span class="icons"><span class="first-icon fa fa-square fa-base"></span><span class="second-icon fa fa-check-square fa-base"></span></span>

I searched a lot, but cannot found anyone with the same problem :(... Its worth to mention, that this is on a blade template file, I'm using fontawesome SCSS with Laravel mix. Does anyone ever got something like this? I have no clue besides that this is fontawesome icons.

I appreciate any help. Thank you very much!