First, have you checked the IRS' Where's My Refund website? It may have information about a correction or an offset. For more details on why your refund could be less than expected, please see this Help Article.
TPG is our third party refund processor if you paid your fees with your refund. For more details on this, please see the Help Article here.
[edited 3/11/22 9:12 AM CST]