The deal increases, rather than decreases, the U.S. involvement with Ukraine, and may make the U.S. Ukraine’s de facto protector. From Andrew Korybko at korybko.substack.com:

That would greatly complicate Russia’s goal of demilitarizing Ukraine and thus imperil the peace talks.
The US and Ukraine finally signed their minerals deal after amending the draft agreement to remove a proposal for Ukraine to pay back past US military aid. A clause was added though whereby future US military aid, including technology and training, is considered part of the US’ contribution to their joint fund. More weapons packages will likely be in the cards since the US now has economic stakes in Ukraine and the value of the aid that it sends to defend them can be counted toward their joint fund.
Such an arrangement imbues the US with more policymaking flexibility than if it had conceded to Ukraine’s demand for concrete security guarantees. Authorizing another weapons package at this diplomatically delicate moment in the peace process could spook Russia and thus lead to the talks’ collapse. At the same time, however, this deal will likely lead to such packages being authorized after a ceasefire on the pretext of defending US investments and contributing to their joint fund.
What this means in practice is that Russia shouldn’t expect the US to fully dump Ukraine in any realistic scenario from here on out. Trump just rewarded Zelensky for this agreement by “inform[ing] Congress of [his] intention to green-light the export of defense-related products to Ukraine through direct commercial sales (DCS) of $50 million or more” according to the Kyiv Post citing unnamed diplomatic sources. This signals his newfound interest in resuming DCS in lieu of large-scale weapons packages.