why images showing 404 when used inspect with .jpg.tmp

Randomly some product images are showing error only when i click inspect.

Error details : Failed to load resource: the server responded with a status of 404 (Not Found). See image below.

enter image description here

i looked around on google and forums, it was suggested it’s permission issue with product images folder. but all permission are correct as per magento.

any help will be appreciated.