Question: There have been countless images of female Iranian supporters dressed in party-hats and looking every bit as casually turned out as any Western women. In view of the recent severe, and brutal, actions inside Iran against women dressed in a way considered inappropriate, could this portend trouble for them when they return?

Equally, at the World Cup match against England, the entire Iranian team stood grim-faced and silent during the playing of their country's anthem. It has been widely interpreted by the media as a protest against the regime that rules in Tehran.

Answer: 
Yes. One of the drawbacks of an authoritarian system of government is that what "the law" is is a bit more opaque. If the current ruling President of Iran (or the current Supreme Leader) wants to punish the players then the players will be punished. Who is there to overrule a leader who is Supreme?

You can argue however that similar traits exist even in much more democratic forms of government; if anyone from local prosecutors or police up the chain in the executive all the way up to the President has a beef with someone, they can do their best to disrupt that person's life using their power to do so. The biggest differences though are that 1) The people in the executive must generally still prove something to different officials in a completely different branch of government before any actions can be taken, 2) those same people are subject to the same set of laws, which usually include harsh punishments for abusing their power against ordinary citizens. Additionally, many of the officials in the executive branch are elected, so in a not very long time they could potentially be held to account for their actions by the people generally, even if any actions they take against people don't rise to the level of criminal. This system of checks and balances against abuses of power just doesn't exist in authoritarian governments.

There have been examples of kidnappings of dissidents by some administrations while they are abroad and even sometimes go so far as outright murder. It is highly speculated that Russia even went so far as to use a chemical agent against defected spy [Sergei Skripal](https://en.wikipedia.org/wiki/Sergei_Skripal) and his 33 year old daughter in order to either silence or exact revenge against, and U.S.-Saudi relations are still being impacted by the murder of [Jamal Khashoggi](https://en.wikipedia.org/wiki/Jamal_Khashoggi) by members of the Saudi royal family (which just so happened to also be audio recorded by the Turkish government).

The balancing act authoritarians must make when dispensing such justice is to find a way to keep the populace subdued enough out of fear and yet not angry enough to revolt, so disappearing the *entire* team is probably not something they can risk doing, certainly not in the wake of the recent protests in the country triggered by the death of [Mahsa Amini](https://en.wikipedia.org/wiki/Mahsa_Amini_protests) while in official custody. They may, however, choose to identify who amongst them is the most vocal and attempt to make an example of them personally or their family in an attempt to silence the entire team (or in this case induce into patriotically singing along), but the range of options the leaders of the country have and can use against any single individual is, in fact, supreme.
We have confirmation now. The rockclimber who competed without a scarf about 6 weeks ago?

Her family house has been [demolished by the government](https://www.bbc.com/news/world-middle-east-63847173). Which claims it was unrelated.

I would also add that the change in behavior of the soccer team, between their first appearances - speech, no anthem - and subsequent avoidance of the subject and singing of the anthem again seems to strongly point to threats of consequences made between those 2 events.