It's insane that in 2026, you can pay for a 4K streaming plan, have a 4K capable PC, connected to a 4K display, with HDCP, Windows 11, latest drivers, latest browser, TPM, Secure Boot and all that other bullshit, but via a web browser, you will not get a 4K stream because of Widevine L1 DRM.
I took out HBO Max recently to get the extra skins in Lego Batman: Legacy of the Dark Knight and watch House of the Dragon Season 3 on.
The stream appears to be capped to 720p, maybe 1080p but the Bitrate must be quite low if that's the case.
You are unironically better off pirating. You will actually be able to watch on a PC in 4K. I will buy the 4K Blu-Ray set when the whole season is done.