Uploaded images classified as files rather than under the media tab In Drupal 8 if you go to admin/content there is a tab for Files and a tab for media.

I believe it is the media entity browser what distinguishes what area an uploaded file will be placed, but I could be wrong on this.

My question is, as well as that, is there an easy way to move files which have been uploaded and placed under the files tab by accident into the media tab without having to re-upload them all?

Thanks for any help on this
Files tab is a view you can add filter by editing this view and based on your filter they can be removed from files tab. Then you can again work on filter of Media tab so that they can display under media tab.

It is up to you what filter criteria you have to move them from one tab to another tab.