Why did I have to pay the IRS taxes on interest of $14.50 I made from them? What was the interest on?

Yes interest from the IRS is taxable income just like bank interest.  They paid you interest for taking a long time to pay your refund, probably your 2020 refund or if you amended a return.   

Why are you asking if the IRS owes you more refund?   Did you get your 2021 refund yet?   

report IRS interest on your next tax return.

@southernway41-ou - if your refund is delayed more than 45 days from the day you submit your tax return the IRS is required to pay interest on the refund.  I assume the $14.50 was interest paid to you due to the delayed refund of your 2020 tax return in 2021....that is income to you, no different than any other interest you receive from a bank. bond, etc. 

currently, the interest rate paid for delayed refunds is 5%.