Images are not shown

Please provide a correct RSS URL because https://ostexperte.de/ is a web page URL. Have a look here, it’s a valid RSS FEED URL https://techcrunch.com/feed/

I had changed to https://ostexperte.de/feed/ but still not working

Please check the demo website, the same URL which you provided is working there.

https://demo.androidbubble.com/

Can you please make sure that your settings are correct?

https://prnt.sc/jl4kxq

Yes it works, but there is no image from blog posts there

Because Feed isn’t coming with images else default settings always honor images it it.