It seems that when we transitioned from HHVM to PHP7, we lost the ability for some JPEG files to read all of the EXIF information that they contain.
Image uploaded on 21 September 2019 and likely parsed by PHP7 https://commons.wikimedia.org/wiki/File:Argenvors%C3%A4%C3%9F_von_S%C3%BCden_2.jpg
Image uploaded before 12 September 209 and likely parsed by HHVM https://commons.wikimedia.org/wiki/File:Wiesbadener_H%C3%BCtte_von_Nordwesten.jpg
These files, uploaded by @Reinhard_Mueller contain MakerNote data, which IS parsed by exif_read_data, but either not fully, or they contain an error. The next EXIF key value pairs at least are missing and when you enable php warnings, I see on the console:
PHP Warning: exif_read_data(Argenvorsäß_von_Süden_2.jpg): corrupt EXIF header: maximum directory nesting level reached in /Users/hartman/Development/wikimedia-git/mediawiki-core/includes/media/Exif.php on line 296