Clean Up App - is it a scam? What should I do?

Yes, it’s a scam. And I’m guessing that they are claiming you have “viruses” installed on your iPhone, which just isn’t true, and as a result are trying to get you to install this cleanup app to remove them. Or you are trying to clean out your iPhone’s storage. Either way, clean up apps do not do as advertised so do not install them. The worst ones will make you pay for it.

even though I'm not stupid enough to sign up for an $8/week subscription.

Unfortunately, that's not how subscription apps on the App Store work. You don't need to 'sign up'. Just launching the app starts a timer on whatever trial period there is; if it even has a trial period and doesn't charge the first subscription fee immediately.

The only way to avoid any further charges is to view your subscriptions and remove any you no longer want. On an iPhone that's:

Settings > your name at the top > Subscriptions

NOT ONLY do these rats start charging me $8 a week for an app that does nothing, but Apple handles the complaint by saying I "asked for it", even though I'm not stupid enough to sign up for an $8/week subscription. Apple directed me to the Cleanup Pro app where I could "ask for" a refund, and Apple told me to wait for 4-5 business days. A week later, my request for a refund was DENIED by Cleanup Pro, and when I called Apple Support (another subscription I'm paying for) back about it, they said nothing can be done" and I will NOT be getting a refund. I filed a dispute with MasterCard and THEY gave me a very hard time, insisting I "subscribed" but filed the dispute anyway.

Yes. It's a scam

What’s the real issue? Why did you ask about Cleanup apps? I wouldn’t think to ask about them unless I felt it might help resolve an issue I’m having. 😀