As it turns out it's fake news.
Seyyed Mohammad Marandi, in charge of the Iranian nuclear negotiation team's public relations with foreign media, categorically rejected this claim by the Wall Street Journal.
As professor Marandi stressed, Iran made no commitment at all in regard to Yemen. There's nothing about Yemen, nothing about Iran-Yemen relations in Iran's agreement with the Saudis, except that parties are expressing hope Riyadh may come to find a peaceful solution to that conflict. Marandi further insisted that Iran's policy towards Yemen is not going to change and that Iran will not betray any of her allies - a point corroborated by history.
Another important aspect alluded to by the latter is that western, exiled oppositionist and domestic liberal media will spare no efforts to try and undermine the deal. One of the narratives they would deploy to this end is to pretend Iran made unacceptable concessions, which they hope would influence Iranian public opinion and exert pressure on the Ra'isi administration.
I'd say in short, let's not pay too much attention to this sort of psy-ops. That an American rag like the WSJ, which is close to the neoconservatives would publish disinformation on the topic isn't surprising.
Listen also to Marandi on Jedaal (the whole program's well worth watching):
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