Trying to transfer photos from flashdrive to MacBook Air

In the photo app, choose File, choose import. This should work fine

https://support.apple.com/guide/photos/from-storage-devices-dvds-and-more-phtae4e05c67/5.0/mac/10.15

Select the photos on the flash drive that you want to transfer. Open a folder on your MBA where you wish to put them, for example, open the /Home/Pictures/ folder. Drag you selection from the flash drive and drop them in the open Pictures folder. This is called Drag and Drop.

If all the photos are adjacent to one another, then you can select all of them by using the mouse cursor to enclose all of them in a rectangle. If they are in a list select the first one, then hold down the Shift key and select the last one. If you want all of the pictures on the flash drive just press Command-A. If the pictures are not adjacent, then you can select the ones you want by holding down the Command key and clicking the mouse on the pictures you want to select.

you could use Photos but I don't ever use it. I use Preview to import my iPhone photos to the Desktop then I use Finder to manage where they go.