Some converted images are not showing in the website

I use webp-express for all my uploaded images, but some of them are not showing.
For instance, https://www.niuniu.com.au/wp-content/uploads/2020/11/2011604377561_.pic_hd-scaled.jpg is converted into https://www.niuniu.com.au/wp-content/uploads/2020/11/x2011604377561_.pic_hd-scaled.jpg.pagespeed.ic.qfwgHpj0wC.webp and it works fine, but https://www.niuniu.com.au/wp-content/uploads/2020/10/a-view-of-a-body-of-water-with-a-mountain-in-the-background-tasmanias-holiday-destinations-will-soon_664683_.png is converted into https://www.niuniu.com.au/wp-content/uploads/2020/10/xa-view-of-a-body-of-water-with-a-mountain-in-the-background-tasmanias-holiday-destinations-will-soon_664683_.png.pagespeed.ic.oWs__bt0Pz.webp and it is not found.
Both images are in the same website and I don’t know why it happens.

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