These are the applicable FAR/DFARS and PSC manual references related to your scenario, in order of the acquisition process:

1. For a given contract action, the product or service code should be selected based on the predominant product or service that is being purchased.  Source: Federal Procurement Data System, Product and Service Code (PSC) Manual, FY2021 Edition. Located at https://www.acquisition.gov/psc-manual.
2. Each contract line item number (CLIN) or subline item shall include the PSC as a data element, FAR 4.1005-1(a)(3).
3. Each synopsis transmitted to the Government Point of Entry (GPE) – beta.SAM, shall include the PSC as a data element, FAR 5.207(a)(5).
4. DFARS PGI 204.606(3)(xiii)(A) – How to report PSC when submitting contract action report to FPDS-NG.
5. FPDS NG - FAQ

There are more, but those are related to other unique scenarios not related to your question.

Bottom-line: Based on the references above, especially the DFARS PGI reference; it is our opinion that you should use PSC that most closely represents the type of supply/service for your task order.  Rationale: there is no guidance that we could find which mandates using the same PSC as was used for the basic indefinite delivery contract.