Is it additional money received by some owners from other owners?

What precisely does the footnote say?

Something like this?

The distributions generated by the fund and wired to your account in 2024 was $XXXXX.  In addition, you also received $YYYYY of equalization payments during the year.  This is attributed to investors coming into the fund late, and paying interest for the right to do so. 

Your K-1 will document the $XXk of distributions, but also includes a footnote explaining the additional $YYk. Footnote says:

IN ADDITION TO YOUR INCOME REPORTED ON SCHEDULE K-1, YOU HAVE RECEIVED ADDITIONAL PAYMENTS PROM THE ADMISSION Of NEW PARTNERS. PLEASE CONSULT YOUR TAX ADVISOR:  $YYYYY