HBO/MAX

I have HBO built into my channel package, so I'm not paying a extra charge for it ala carte. Of course HBO MAX is part of HBO, so I have a question about the upcoming tier changes in Max. Will this affect my Comcast bill? What I'm concerned about with Max is that there may be ads, but the biggest thing for me is the basic info I read said in would be HD, no mention of 4K. Part of the point of MAX is you can view things in 4K, HBO doesnt. just HD. How or  will these upcoming changes affect me?

BTW I still don't understand why Comcast and the cable channels it carries (not counting internet content like MAX, Netflix etc) are not broadcast in 4K, just HD