Open .jpg-files will always open the same file

When clicking on a item the image will be shown. This works für Microsoft Edge and Google Chrome, but not for Mozilla Firefox.

Example: https://www.hospizkreis-ottobrunn.de/allgemeine-dokumente/#elf_l1_NCBCaWxkZXJnYWxlcmllLzIwMjMvV2VsdGhvc3BpenRhZyAyMDIz

The page I need help with: [log in to see the link]