I've never cleaned mine, just drain it before putting it away. It's not clear by any means but still flows great after about 15 years.
Maybe does the hose have a kink somewhere in the line? I have a hose set up that is most likely 15-20 yrs old. And it has a few linked areas that I have to physically open up myself.
I’d say that kink is your problem. I have creative ways of looping my hose to avoid kinks like that. Haha. I do have the green hook but it leaks so I don’t use it. But maybe getting one would work for you. No kinks then.
I too have never cleaned my hoses. Just drain and roll it up at shoulder high to make sure all water flows out. I also keep mine out in the open so mold does t grow while it dries out.
Something else to consider... how is the water pressure in your house? Has that seem to have changed?