Hello @EricZhang456, per #11048, please opt into Steam's client beta and retest.
It works in the beta client
still broken to this day...
Unsure if this is been reintroduced or a new bug, but this still is happening, even on the beta branch.
Nothing extracted yet.
Your system information
Please describe your issue in as much detail as possible:
Right clicking on a screenshot in the Screenshot Manager and selecting "Copy to Clipboard" should copy the image to the clipboard
Steps for reproducing this issue: