This took the index some more time, but after around six weeks, the blocked images are no longer displayed as search results.
I am not sure if this will help for future uploads for photos of the same people with different filenames, but I had added strings with placeholders like these:
User-Agent: Googlebot-Image
Disallow: /wp-content/uploads/*adam*smith*.jpg
Disallow: /wp-content/uploads/*adam*smith*.png
Disallow: /wp-content/uploads/*eve*miller*.jpg
Disallow: /wp-content/uploads/*eve*miller*.png
Disallow: /wp-content/uploads/2019/03/domain.eu-adam-smith.png
Disallow: /wp-content/uploads/2020/02/domain.eu-team-eve-miller.jpg