DRM seems to be broken on Safari 14 Catalina

Did anyone upgrade Safari from 13 to 14 on Catalina? Everything was fine until I upgraded Safari this morning and Netflix started to report Error Code S7760. I thought this is related to DRM and tried to playback Amazon Prime Trailer according to Dortania's DRM guide, which works fine. Apple TV+ is fine too by the way, so it doesn't look like the DRM is completely broken.

I'm not sure whether this is a WhateverGreen patch issue or something to do with Safari itself. I mean, aren't both Prime Trailers and Netflix suppose to use hardware FairPlay 2.0/3.0 decoder according to manual? Why would Netflix seem to be broken while Prime Trailers are fine?

my specs and configurations:

• iGPU + dGPU
• SMBIOS: iMac19,1
• shikigva=80

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