Since poppler seems to have issues I needed something else to extract text from image files. Tesseract does the trick (install tesseract). Made a simple dolphin servicemenu for it. In case someone needs it. Just place it in ~/.local/share/kservices5/ or ~/.local/share/kservices5/ServiceMenus ( if you should have a subfolder for the stuff). https://imgur.com/a/M6BA7iu https://imgur.com/a/tFH6aM1

[Desktop Entry]
Type=Service
ServiceTypes=KonqPopupMenu/Plugin
MimeType=image/*;
Actions=ExtractText;
X-KDE-Priority=TopLevel
X-KDE-StartupNotify=false
Icon=document-sign

[Desktop Action ExtractText]
Icon=document-sign
Name=ExtractText
Name[en]=ExtractText
Exec=tesseract %f output.txt