Thumbnail size problem Desktop vs Mobile site

I have a problem with the thumbnail

I setup Customizing ▸ WooCommerce ▸ Product Images

The desktop page version shows a smaller thumbnail and the mobile site show the biggest version, Google page speed I got bad results because the mobile site is bigger than the desktop. Category grid view have 100 pictures and too mutch size

So way working opposite?

Mobile site version picture size 68 Kb. Desktop site version size 41 Kb.

Somebody can check reakiroshop.eu

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