When using OBS Browser Source, that is a different Browser from any you've installed at the Operating System level (a version of Chrome, if I recall correctly and I may easily be not remembering... see release notes for details. If I recall correctly, the OBS Browser is NOT updated any near the frequency of native Chrome).
To avoid bootlegging (terms of service violation, illegal in some areas) of copyrighted content, some streaming platforms copy-protect their streams. Most likely, the OBS Studio provided browser does not meet whatever requirements the streamer (in this case Spectrum) has decided to impose.
So, instead of [OBS Studio built-in] Browser source, use Window or Display Capture and capture your Operating System running browser of choice. However, don't be surprised if copy-protection interferes.
Also, OBS Studio is designed for compositing.. ie combining multiple Audio and Video sources. OBS Studio is a fairly complex tool, and is overkill for a simpel Screen Recording (native tool in Operating System). That isn't to say there aren't good reason to use OBS Studio...