What a WebP file actually is
WebP is Google's 2010 format, derived from the VP8 video codec. It offers both lossy and lossless modes and, unusually, supports transparency in both — the reason it can replace JPG and PNG with one format. Google's own comparisons put it roughly 25–35% smaller than JPEG at matched quality.
Files usually arrive as WebP because they were saved from a website: browsers and CDNs serve it widely, so 'save image as' on a modern site frequently produces a .webp you then cannot open in the application you needed it for.
What you get from PNG
PNG output is lossless, so the saved pixels are exactly the pixels that went in and re-saving costs nothing in quality. It keeps a full 8-bit alpha channel, which means soft shadows and anti-aliased edges survive against any background.
Universal since the early 2000s, and the format every design tool, browser and operating system handles without argument. It is also the safest format to hand to a printer or a colleague when you do not know their software.
What changes when you convert WebP to PNG
PNG is lossless, so the conversion preserves exactly what the WebP decoded to — but not the detail the WebP had already discarded. You are freezing the current state, not recovering the original, and a common misunderstanding is that saving to PNG somehow restores quality. Expect the file to grow, often several times over, because lossless compression cannot match what lossy compression already did.
Transparency survives intact. Both WebP and PNG carry a full 8-bit alpha channel, so cut-outs, drop shadows and anti-aliased edges convert without a white box appearing behind them, and the result still composites cleanly onto any background colour.
WebP files are a mixed bag, because the format has both a lossy and a lossless mode and nothing in the filename tells you which one you have. A lossless WebP — typically a graphic or screenshot — converts to PNG with the quality trade described above; a lossy one has already been through a codec once. If the image has flat colour and hard edges, treat it as the former and keep the quality setting high.