SIze of entry pictures

Hi, me again,

I am having a little problem with the size of the entry images.

In the first posts the image was complete on the homepage and fully shown in the entry – just a little bit smaller.
See here: https://kopfkino.sasverse.de/neleneuhaus-boeserwolf/

In the last entries both images are cut automatically.
Like here: https://kopfkino.sasverse.de/the-fault-in-our-stars/ or https://kopfkino.sasverse.de/georgepelecanos-dertotengarten/

I can’t remember that I changed anything image related and I couldn’t find any setting for it.

Can you help me out? Did I do something wrong?

Thank you, Sas