Ukraine likely also has money and needs cheap drones.
Ukraine doesn't really have money. It's mostly NATO, and the US specifically, that have money; even if Ukraine has some money to spend on its own - it would still be subject to US scrutiny. And that money will not buy Iranian products, including drones.
Moreover - military drones are not simlysimply consumer off-the-shelf products - they: They would require some level of cooperation between the Iranian military-industrial sector and the AFU. Here again, US/NATO control would likely not allow this (if the Iranians were inclined to offer such a thing, which they likely aren't, see below.)
the EU, the US, and other world powers that are standing on Ukraine's side.
Well, it's debatable whether they're actually standing on Ukraine's side, but be that as it may, world states which can be said to be in that category are the US, most EU members, and Australia and Japan, which are strongly US-influenced - if we choose as our criterion sanctions against Russia (see map) ; and other countries are not taking sides strongly, or are neutral, or are supportive of Russia / opposed to NATO expansion.
In particular, Iran is a key member of BRICS - the block of states which could be said to be in opposition to US hegemony (or US-European hegemony). BRICS countries are not supporting the NATO side of the proxy war (i.e. not "standing by Ukraine") - and Russia is one of them. If not a weapons embargo on both sides, it makes strategic sense for Iran to sell drones to its block-ally, Russia, especially since it was, and is, the likely military victor in the war.