Given that Spectrum is a mish-mash of at least three different companies and not at all monolithic and this seems to have started for everyone reporting it at the same time, it seems the weak link in this must be Blizzard (but even that isn’t certain).
It could simply be that the “best” route between Spectrum’s/Charter’s/TWC’s system and Blizzard’s system goes through some damaged or mal-configured part of the backbone.
These things are incredibly complex and I don’t have the tools to diagnose it from home, but I’m not seeing anything that would tell me that Spectrum, per se, is having any sort of systematic problem outside of a few spots near Albany NY and Los Angeles California.