Solution for this topic

Hi Sofia,

Thank you for your question.

I visited your shared site and it seems you are using Jetpack plugin on your site so could you please try temporary deactivating its Photon module on your site as shown in the attached screenshot?

This jetpack photon module is not updating the images stored on wp.com so to resolve the issue either disable this module or update the images on wp.com by contacting jetpack support team.

Then try regenerating thumbnails using the below plugin.

https://wordpress.org/plugins/force-regenerate-thumbnails/

Best regards,
Shufflehound team