"EIP" is in the code for EIP, such as TAXEIP3; if that is the only thing, it would show this. Tax Refunds are coded TAXREF. 310 means electronic payment (direct deposit, not by paper check or prepaid card). PPD is banking:

"Prearranged Payment and Deposit (PPD)
Prearranged Payment and Deposit (PPD) is the Automated Clearing House (ACH) format used by the federal government for consumer payments."

"Standard Entry Class Code
The Prearranged Payment and Deposit (PPD) is the SEC code used for identifying federal agency consumer payments. The payment entries may be accompanied by a PPD addenda record (PPD+) which further identifies the reason for the payment."

Because there is no specific code here, their tax account transcript would show more details. It likely is a combination, and since you stated it is less than expected, there may be a follow up payment once the return is reviewed. Yes, if you filed 2019 and 2020 late, they would not pay out everything until penalties and interest are determined.