Russian investigators recently uncovered an abandoned Kiev regime chemical weapons laboratory in the now-liberated Donetsk People's Republic city of Avdeyevka.
If chemical weapons had been used at meaningful scales, it would have been known by now.
I think it's safe to say that these biological/chemical labs are big nothing burgers -- just small labs that were paid for by the US to keep experts employed so that they didn't wander off and sell their skills to people that might make use of them after the collapse of the USSR.
Going with the US state department line on this one, unironically.
I'm assuming there's an unspoken /s after this, because I'm trying to figure out what about Ukraine having chemical weapon labs long before the invasion near the Russian border is Russia's fault.