Hi, SomeoneWating
Welcome to the Microsoft community.
Theoretically, the information on the edge://gpu/ page is internal data from Edge and is generally the most accurate. The higher CPU usage compared to Firefox may be due to some optimization issues. (Additionally, if hardware acceleration is disabled, many other features on this page would explicitly notify you that they cannot function due to it being turned off, so it should be enabled. The "video encoded" function is also in the "Software" status on our side, so it should not be an issue.)
At the same time, Edge on Linux is not within the support scope of this forum. You can visit Microsoft Learn for further assistance.
Microsoft Edge - Microsoft Q&A
Sincerely hope that your question will be dealt with appropriately after contact the correct department. Thank you for your understanding!
Best regards
Tommy Jin | Microsoft Community Support Specialist