Of course, paying any product fees out of the Federal refund (if applicable) and its service fee will reduce the refund, but not to that degree. So that would not explain *your* situation.
If the IRS decreased your Federal refund, you should get a postal letter from them in 2-3 weeks or so explaining why your Federal refund is less than what you filed. The letter should also tell you steps you can take if you disagree with their decision, including a contact number for you to phone them if desired. The following help article will tell you a bit more about possible causes, how to check for any offsets, etc.
https://ttlc.intuit.com/questions/1894477-why-did-my-federal-tax-refund-decrease-after-i-filed
The IRS has said:
"Examples that could decrease your refund include math errors, mistakes, delinquent federal taxes, state taxes, child support, student loans or other delinquent federal nontax obligations, and when the IRS withholds a portion of your refund, if further review is needed."
https://www.irs.gov/Help-&-Resources/Tools-&-FAQs/FAQs-for-Individuals/Frequently-Asked-Tax-Question...
IRS: 800-829-1040 hours 7 AM - 7 PM local time Mon-Fri
If an offset is involved, here's more info on the Treasury's offset program:
https://ttlc.intuit.com/questions/2539782-what-is-a-refund-offset
Treasury Offset Program phone: 800-304-3107
Offset Call Center hours are 7:00 a.m. until 6:00 p.m. (Central Time).
