I sense some changes coming in sanctioned oil (Iran as you mentioned, Venezuela possibly).
Reading the news I sense that too but the evidence suggests otherwise.
I can't speak of Venezuela but Iran's sanctions were too long that Iran already found customers to sell oil to (including Europeans!). So in a way there is no need to sell any additional oil to Europe anymore, specially now that Iran is increasing pressure on the West for 43 years of sanctions.
In fact if any sanctions were to be lifted, there is a good chance that mostly Russia oil reaches European markets through Iran.
Hint: A little more than 2 months ago Greece seized an Iranian oil tanker and Iran responded by seizing 2 US oil tankers. The Iranian tanker was actually carrying Russian oil and was heading towards Western Europe.
Already Russians are transporting part of their oil in the stealth mode. Ship-to-ship transfers are taking place and Asian as well as European refineries are being used to produce finished products sourced primarily from the Urals crude. With prices remaining constantly above $100 per barrel, there will be a lot of demand for cheaper crude (not just from the third world nations, but also from the developed ones). Iran is definitely going to be one of the beneficiaries and as mentioned above, I foresee a large part of Russian crude supplies rerouted through Iran in the near future.
This is very likely. But I do not think that the United States will allow this before reaching an agreement on the Iranian nuclear file. Tehran still has to make concessions to reach an agreement, and time is not on its side if America continues to delay the procedures. America is not in its interest to break Iran's isolation. Yesterday, the infrastructure of the Iranian Revolutionary Guards was destroyed in Syria by American planes, and Israel, on the other hand, reiterated its clear refusal to reach an agreement with Iran, as it does not want it to become a nuclear state (this will weaken the balance of power on the ground).
The biggest problem for European countries is not oil in the first place, because they can pressure producers to increase production, including Venezuela. The great crisis in the Russian invasion with the approach of winter. Gas is Russia's trump card in this confrontation.