I have never heard of any threshold under which you don't have to report income. I also make less than $50/yr on itch.io (we should form a club!) but I still report it (minus the itch.io and paypal cut) as self-employment business income on schedule C (and of course I deduct self-employment business expenses, such as app store registration fees, game engine licenses...which is a nice thing about having your own business.
https://www.irs.gov/businesses/small-businesses-self-employed/self-employed-indi...
Of course, I am not a tax lawyer, accountant, or IRS representative, so you might want to check with one of those to be sure.
Edit: there is a minimum threshold for total income that affects the requirement to file a tax return, but I gather as you're filing anyway, that's not the issue.
https://www.thebalance.com/are-you-required-to-file-a-tax-return-3192868