What does converting WebP to JPG actually do?
WebP was designed to replace both JPG and PNG on the web: lossy mode typically beats JPEG by 25–35% at matching quality, lossless mode beats PNG by around 25%, and both modes support an alpha channel. Every current browser supports it, though some older desktop software still does not. JPEG discards detail the human eye is least likely to notice, which is why a photo can shrink by 80–90% with no obvious visual difference. The trade-offs are permanent: there is no alpha channel, and every re-save recompresses the image, so repeated editing slowly degrades it. Converting WebP to JPG therefore re-encodes the same content under a different set of rules — the pixels are decoded from the source image and written out through the destination encoder. Nothing is uploaded: the decode-and-re-encode cycle happens on your own machine.