Photo rotation in slideshow

I saw a conversation from 2021 re: photos being rotated in slideshow AFTER having already been correctly oriented within Photos. People seemed to imply that it was related to a software update...11.??? to 11.???. (I'm not a software specialist :) I just wondered if anyone has found a way to fix this.

I am cleaning out an organizing my 20+K Photos library and hoping to enjoy my photo slideshow as screensaver. But now a lot of my scanned older photos keep showing up sideways....yuch!

I followed someone's advice and tried exporting a small batch out of Photos, then choosing that folder for my screensaver slideshow...and it worked fine :) But I hate to have to search them all out (which is hard since within the main Photos library, they are all oriented correctly) and save them to a folder outside of Photos to use for my slideshow.

Any new advice?

Thanks.