I believe that this is the best answer for your situation. Just don't report it.
You are correct that this is not self-employment. You are simply one of the first to get a 1099K from Paypal for sales that are less than the intended threshold.
The IRS requires each payment settlement entity to send you a Form 1099-K by January 31 if it has processed at least $20,000 worth of payments and at least 200 transactions for you in the previous year.
Due to recent changes in the law, payment apps like Paypal will be sending these 1099-K's to millions of people like you who did not do $20,000 worth of transactions. The new threshold is $600 and that is completely ridiculous. I predict that this law will be changed before 2022 taxes are due.
Just keep the 1099-K with your tax records. And make sure you cheer the tax expert who told you not to file it. That is excellent advice.
