Loop through the subcategory array if you have array
@foreach($projects as $project)
@if(isset($project->subcategory) && !empty($project->subcategory))
<p>
@foreach($project->subcategory as $subcategory)
{{ $subcategory }}
@endforeach
</p>
@endif
@endforeach
Updated
but you have string in the subcategory, this can also be done with regex.
@foreach($projects as $project)
@if($project->subcategory != '')
<p>
{{ str_replace(['"',"[","]"],'',$project->subcategory) }}
</p>
@endif
@endforeach
Updated this regex can also be used
preg_replace('/[^a-zA-Z0-9,]/', "", $project->subcategory)