There is no proof that Iran has supplied Russia with attack drones of the model Shaheed-136. This is the official word from the Iranian government, and we should definitely trust a regime that has a history of lying through their teeth, killing their own people and sponsoring international terrorism.
Russia has trouble producing enough conventional weapons, as indicated by Putin's recent order that the Russian war industry must strengthen their efforts and increase production, but they obviously made thousands of drones themselves. The drones are identical in design to the Iranian Shaheed-136, down to the last nut and bolt, but Russia has obviously made a huge effort to copy them rather than simply buy them from a country that has voiced its support for Russia's illegal aggression towards a friendly neighbour.
I mean, the drones have Cyrillic letters on them, right? It's not as if they could have been repainted or anything. A paint job is far beyond the capabilities of the Iranians or Russians. No, these are Russian made, through and through, produced by magical means by a Russian industry that struggles to produce weapons even of their own 1970's design, and the Iranians had absolutely nothing to do with these drones. Because they said so.