As it stands, it is unproven if Ukraine has used chemical weapons on Russia.
Many articles have reported on the claim, but it is written within each that Russia has made the claim without any actual evidence.
Russia has claimed that Ukraine's Armed Forces have used chemical weapons near the Ukrainian towns of Soledar and Bakhmut using drones without evidence as explained by Reuters, "Russia's Investigative Committee said the Donetsk People's Republic, one of Russia's proxies in the territories it has seized and occupied, had reported the use of chemical weapons by Ukrainian drones near the two locations. The allegation was not accompanied by any publicly released evidence."
Ukraine has put out a statement denying the claim, stating, "The enemy's accusations of the use of chemical weapons by units of the Armed Forces of Ukraine are untrue..."
It is also important to note as pointed out by Reuters that "Since the start of its invasion nearly a year ago, Russia has repeatedly warned that Ukraine might be preparing to use non-conventional weapons, including biological weapons or a radioactive dirty bomb. No such attack has materialized."
Right now, Russia has no physical, concrete evidence that Ukraine has utilized any sort of chemical weapon and there has been no evidence of any sort of attack since the start of the war. That makes it highly likely that the claim is false, but it is not proven.
As for the twitter video, its validity is unknown. I could not find anything about it, so it is unknown that if what is being shown are indeed chemical weapons, if that video is taking place in Ukraine, or even if the men in the video are part of Ukraine's Armed Forces.
https://www.reuters.com/world/europe/without-supplying-evidence-russia-says-its-investigating-alleged-ukrainian-use-2023-02-06/
