I checked with the Nazi AI and Iran did not make this claim.
A few Twitter users made this claim, but it cannot find Tasnim state media or the Iranian army making this claim of destroying grounded Israeli F35's in 2024.
Based on the available information, there is no direct evidence that the Iranian army claimed through their state media that they bombed 20 Israeli jets in 2024. *nstead, this specific claim appears to have originated from other sources, such as Israeli sources and IranIntl (a Persian-speaking Israeli outlet), rather than from Iranian state media outlets like Tasnim News Agency or statements directly attributed to the Iranian army or the Islamic Revolution Guard Corps (IRGC).
It even states that this misinformation about 20 destroyed jets originated from Israeli sources which is interesting. Not sure if true but at least not from Tasnim.