thumbnail gets smaller after each post

I am using the Generatepress theme. I keep making test posts and looking at the blog page listing the posts, the thumbnail for the default featured image is smaller for each post… keeps getting smaller and smaller. I do a post with uploaded featured image (not default) and that is ok… right size… so I know it’s only if I don’t add featured image and it uses default.

I even resized the image in photoshop to be the right size… I thought maybe the image had been too small and was trying to fit. But if I keep posting posts, the thumnail gets smaller and smaller still after each post… each post smaller than the last.

What do I do?

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