As mentioned earlier, the bulk of material going to Ukraine, are older and were pulled out of interim storage.
The US M2/3 Bradley AFVs, for example, were drawn out of retired stocks. The current Bradleys in U.S. service are intended to be replaced by the finalized XM30 product of the Army's MICV program.
Ukraine has received 190 Bradleys out of just about 7,000 manufactured.
In the case of the U.S. Army TACMs (ATACAM), they are the older version (M39) drawn from storage.
The USN will not part with any of their current or stored TACM stocks, as they have stated that all are ear-marked for "potential use in the Pacific".
The M1 Abrams tanks heading to Ukraine, are the older M1A1 version, which are also being drawn from storage.
The same goes for other nations, who are donating older Leopard tanks or in the case of the F-16, which is in the process of being replaced.
Another example, is old artillery stocks, which has the benefit of jump-starting new and accelerated production. This has the benefit of both providing Ukraine with what she needs, but also bolstering various nations with new munitions in most likely larger numbers that were had previously.