Further, from the IRS partner instructions:
Partner’s Instructions for Schedule K-1 (Form 1065) (2023)
Partner's Share of Income, Deductions, Credits, etc. (For Partner's Use Only)
https://www.irs.gov/instructions/i1065sk1
About 75% of the way down:
"Code AG. Gross receipts for section 448(c). Regulations section 1.163(j)-2(d)(2)(iii) requires that partners in a partnership include a share of partnership gross receipts in proportion to their share of gross income under section 703 (unless the partnership is treated as one person under the aggregation rules of section 448(c)). Partnerships with current year gross receipts (defined in Regulations section 1.448-1T(f)(2)(iv)) greater than $5 million are required to report to their partners their distributive shares of current year gross receipts, as well as their distributive shares of gross receipts for the 3 immediately preceding tax years. If a partnership and a partner are treated as a single employer under the section 448(c) aggregation rules, and the partnership has current year gross receipts greater than $5 million, then the partnership should also report its total current year gross receipts, as well as its total gross receipts for the 3 immediately preceding tax years, to that partner. See IRS.gov/newsroom/ faqs-regarding-the-aggregation-rules-under-section-448c2–that-apply-to-the-section-[product key removed]ess-exemption.
If a partner needs gross receipts information from a partnership in order to figure the gross receipts test under section 448(c), and the partnership didn't report gross receipts on the Schedule K-1, the partner should request this information from the partnership."
