The offer was made in the days following the NYCFC's MLS Cup final victory over the Portland Timbers, a match in which Castellanos scored in regulation time as well as in the penalty shootout, but the sources have added that the amount doesn't yet meet the Blues' valuation for the player -- NYCFC are seeking in excess of $15m.
In 35 league and playoff appearances this season, Castellanos scored 22 goals and added eight assists while winning the Golden Boot. In parts of four seasons with NYCFC, he scored 40 goals with 18 assists in 99 league and playoff appearances.
In a recent interview with ESPN, the 23-year-old revealed that he dreams of playing in Argentina, but made it clear that he is focused on a move to Europe, where he said he already has offers.
"Obviously, it's a desire I have, because I've never played in Argentina," he said via a translation. "But I don't think the time is right now. I want to aim for European football. It's reality, it's my dream, I always wanted to [play] there. That's my focus. Today I have many offers from Europe."
This isn't the first time that Palmeiras has pursued the Argentine. Last May, Palmeiras made an offer of $4m for 70% of the economic rights of the player. However, the American club, which at first had liked the proposal, withdrew from negotiations. NYCFC subsequently signed Castellanos to a new five-year contract through 2025. According to data from the MLS Players Association, Castellanos' guaranteed compensation in 2021 was $776,000.
A native of Mendoza, Argentina, Castellanos originally joined NYCFC on loan in 2018 from Uruguayan side Montevideo City Torque, another City Football Group club. The Blues activated an option to purchase Castellanos after a successful loan stint which included a goal in his debut against Vancouver Whitecaps.