Featured image size

Hi,

I just moved my staging web site to production. Everything it seems ok, just all featured images changes size between two versions:

https://dev.marconoris.com/the-triumph-of-defeat/
https://marconoris.com/the-triumph-of-defeat/

In the first case, staging, images are resized with a “?resize=825%2C510&ssl=1” tag after file extension, but in production no.
How can I do to resize featured images in both sites?

Thanks ??
m

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