The Polish proposal was most probably a response to the behind-the-scenes talk, regarding the potential transfer of the MiG-29 jets to Ukraine. The jets in question could be adopted, relatively hassle-free, by the Ukrainians, as the Ukrainian Air Force has been a long-time Fulcrum user. Nonetheless, the Ukrainian Fulcrum inventory included different variants of that airframe. Meanwhile, the transfer of the western fighter aircraft to Ukraine remains ungrounded, given the lack of proper training.
Poland, for a few days now, has been pressured into giving away its MiGs to Ukraine. The idea first originated more than a week ago, and it is attributed to Ukrainian sources. It seems that Poland has been surprised by the aforesaid proposal. The proposal to transfer the jets to the US did not meet a positive appraisal.
John Kirby, the spokesperson for the Pentagon, responded to the Polish statement a few hours later, saying that: The prospect of fighter jets at the disposal of the Government of the United States of America departing from a U.S./NATO base in Germany to fly into airspace that is contested with Russia over Ukraine raises serious concerns for the entire NATO alliance. (...) It is simply not clear to us that there is a substantive rationale for it. We will continue to consult with Poland and our other NATO allies about this issue and the difficult logistical challenges it presents, but we do not believe Poland's proposal is a tenable one. Considering the above, it remains unclear whether NATO would face more trouble selecting the transfer from a German base, or the Polish location.