Hi Nadine,
Since your affected aircraft are mostly Traffic Aircraft (AI Craft), your problem is with the generic aircraft. These are installed to the Official Packages folder, the same as where the fs-base folders are.
You’ll need to delete the files for them and let the sim redownload and extract them.
This is relatively simple. In your Official Packages folder, use the search bar and type “generic” you should see some file names starting with asobo. Delete these folders and then restart the sim. It will redownload them and should resolve the issue.
This thread has some more detials: Pink Textures On Aircraft
If this doesn’t work. I’d suggest starting a new thread under community support to get some help since this thread has been resolved.