maybe your alt tag shouldn't be so long and should only be more like just
"raimund schucht"
?
and then when you google raimund schucht, maybe they will just show up?
"Siemens Innotrans, 2022, Messe, Kunde: Siemens Mobility, Agentur: BEYOND FUTURE one GmbH, Berlin, Entwurf & Szenografie: Raimund Schucht Raimund Schucht Szenografie"
also as you see your alt tag has your name in it two times at the end and maybe it penalizes that, not sure
look:
Screenshot 2024-02-28 at 17.44.33.png
you have this setting in lay options.
so this is how it works:
if that textfield above is empty. all alt tags will just use your site title. which is "raimund schucht szenografie"
if sth is in the textfield all your tags will be the text in the textfield
if you enter the alt tag for the image in the media library for example, that alt tag will be used and the text in the screenshot above (if there is one), will be added to the end of the alt tag