Each month I receive these charges on my credit card, but I see them nowhere on my subscriptions. What channels do they pertain to? If they are the basic cost of using Roku then why doesn't the billing account indicate that fact.
There is no "basic cost of using Roku". Roku is free. The first one is likely Paramount+. The second might be some premium service accessed through "The Roku Channel".
Start here:
Charges you don't recognize on your Roku account | Official Roku Support
If nothing there can explain it, you'll have to contact account/payment support at https://support.roku.com/contactus.
I did not give permission to charge me extra fees on my credit card for roku.
@Helenahampton68 If you suspect these are not valid or fraudulent charges, reach out directly to Roku customer support on their support page. I would also reach out to your credit card provider and report as fraudulent so that they can investigate the issue for you.