There's this quote from Ukrainian FM Kuleba doing the rounds on social
media, essentially talking about a quid-pro-quo: more Patriots in
exchange for less attacks on Russian oil infrastructure (which the US
opposes)
This is not an accurate description of why the U.S. is not currently sending more aid to Ukraine. It is a tempest in a teapot side issue.
Is the US acknowledging that they're losing some leverage over Ukraine
by cutting off aid?
The question seems to assume that the U.S. speaks with one voice on issues like aid to Ukraine and that cutting off aid is a unified rational choice. Of course, that isn't how U.S. politics work. Political power is much more widely distributed than in countries with parliamentary systems of government that fit the kind of governance model that the question assumes. The key decision makers in the U.S. government are currently divided, leading to gridlock, which is the default mode of American politics.
The U.S. in not a monolith. The loss of leverage is widely acknowledged by advocates of U.S. aid to Ukraine. The loss of leverage is ignored by opponents U.S. aid to Ukraine, some of whom are pro-Russia or at least not pro-Ukraine, and many of whom feel that the U.S. has no business involving itself in foreign wars to which it is not a party at the expense of U.S. taxpayers.
The Biden administration is doing everything it can to get aid to Ukraine, despite its desire to have some mild influence on one tiny part of Ukrainian military strategy related to strikes on Russian oil facilities.
So is Republican House Speaker Johnson, along with a majority of House Republicans.
So is the Democratic party minority in the House and the Democratic party majority in the Senate.
But Republican conservatives in the House, who make up a minority of House Republicans, don't want the U.S. to authorize more aid to Ukraine and are preventing the U.S. from taking action to provide more Ukraine aid. They have the power to do so because they have the votes to remove Republican House Speaker Johnson from office if he moves forward on Ukraine aid without their tacit consent or at least without their strong objections.
The opposition of conservative House Republicans to Ukraine aid has essentially nothing to do with a desire to prevent Ukraine from striking Russian oil fields. Their opposition to this aid is instead driven by domestic political attitudes towards foreign military aid and Russia generally. Some Republicans, at least, have rethought their historical opposition to all forms of military actions by Russia and Russian proxy wars that was an article of faith for them during the Cold War. They did so after President Trump took a more conciliatory attitude towards Russia.
Senate Republicans are breathing a sigh of relief that this issue, which is a source of division within their political party, isn't their problem yet since spending bills have to start in the House. Some Senate Republicans support Ukraine aid and others do not. But the number of Senate Republicans who support Ukraine aid is large enough, in combination with Senate Democrats who support Ukraine aid, to overcome a Republican filibuster of spending for this purpose. And, as a minority party in the Senate, Senate Republican have little control of the agenda unlike Republicans in the House.