When I paste an image from Flameshot (which can save to the webp) via the clipboard, Obsidian converts it to png (which weighs much more).
Things I have tried
I tried to find the option to select the embeded file to change png to webp in the Files&Links section, but unfortunately I did not find such an option.
It would be great if there was such native opportunity or at least a third-party plugin.
What OS are you on? Depending on your OS, maybe someone could suggest a workaround. For example, in MacOS I bet Alfred App or AppleScript could make a macro/workflow that would move the file into your attachments folder, and then paste the embed link directly. (For example)
Otherwise, I know webp works if you drag the file in, instead of pasting.
Another thing you could try is go to this website and paste your clipboard there to analyze what type of data is being stored in your clipboard. Maybe there is a clue for why it’s pasting as png instead of webp.
I also put .webp in my notes just changing their extension to .png before dragging and dropping them into Obsidian. They work perfectly .
Obsidian believes they are real .pngs but they take up much less space in memory