In plain English
FAR 52.228-12, Prospective Subcontractor Requests for Bonds, is a contract clause prescribed at FAR 28.106-4(b), most recently dated Dec 2022. The complete official text is reproduced below, verbatim, from GSA's published FAR source files.
Its text contains no sentence requiring insertion into subcontracts; see the flowdown section below for what that does and does not mean.
Does it flow down to subcontracts?
No flowdown mandate found in the clause text
We scanned the full clause text and found no sentence directing the contractor to insert this clause into subcontracts. That is a statement about the text, not legal advice: a prime contractor may still flow terms down contractually, an agency supplement (DFARS, VAAR, …) may add requirements, and clauses listed below (if any) may order this clause into subcontracts from the outside.
Where it's prescribed
As prescribed in 28.106-4(b), use the following clause:
Prescribing reference: FAR 28.106-4(b).
The official text, verbatim
As prescribed in 28.106-4(b), use the following clause:
Prospective Subcontractor Requests for Bonds (Dec 2022)
In accordance with section 806(a)(3) of Pub. L. 102-190, as amended by sections 2091 and 8105 of Pub. L. 103-355 (10 U.S.C. 4601 note prec.), upon the request of a prospective subcontractor or supplier offering to furnish labor or material for the performance of this contract for which a payment bond has been furnished to the Government pursuant to 40 U.S.C. chapter 31, subchapter III, Bonds, the Contractor shall promptly provide a copy of such payment bond to the requester.
(End of clause)