They may not consider it an issue. Report it to the Feedback Hub for consideration by the development team. You can post a link to the feedback here and others can add comments and upvote in the Feedback Hub.
I've never seen an issue with pasting in search as I've always typed in, that still works for me without a problem on 1909. If I should want to paste I would use ctrl+v.
Other users here cannot change how Microsoft have developed the search function in File Explorer as we are all users like yourself and not MS employees.