Perhaps they are but I wouldn't expect the FBI to share those details with the world because it tends to fuck up investigations when you tip people off.
The argument about security for Harry and his family on British soil is a different matter. The High Court gave him leave to challenge the Home Office's refusal to fund police protection for him and Meghan while in the UK. That is trundling on and has cost £200,000 in legal fees so far and will cost more but is completely in order,
The High Court ruled there should be a review because the decision might have been unlawful. The Home Office and other government departments have made mistakes over the years. Usually they involve ordinary British citizens but this time celebrities are involved. But the issue is the same - the High Court says the Home Office has questions to answer.
Harry is paying his own bill but the Home Office are using taxpayers' money. That's also completely in order though if the Home Office's decision is ruled to be unlawful, questions might be asked about the wisdom of the original decision and their decision to defend it.
Before this legal challenge there were stories that Harry wanted to pay for his own security and/or use his own protection officers while here. That was refused. Rightly, in my opinion because no one is supposed to be able to hire any of the police forces in the UK like they are private security firms. There would also be a major problem with government or private citizens of any nationality carrying guns on British streets, let alone using them. Though it would be foolish to believe that President Biden didn't bring his own armed security team with him when he went to Queen Elizabeth's funeral and that all other US presidents who have visited Britain didn't too.
Harry might pay for private security in the US where it would also be legal for him and his protection officers to carry guns. I don't think Britain makes any contribution to that because if we were there would be no cause for the argument with the Home Office about protection on British soil.
In the US the FBI would only get involved if there was evidence of an interstate crime or conspiracy. Again, who knows? There might be but they don't confide in me.
If not I would expect it to be a job for the state police in Harry and Meghan's home California or other states they visit such as New York if it happened there and there alone. Rest assured that wherever that happens in America only the American taxpayer is going to have to pay for it.
The FBI and other US police forces or US government agencies have no jurisdiction in the UK or any other foreign country unless it is granted which it sometimes is. Sometimes that's understandable but sometimes it is granted even though it is not because the US are powerful.
I would prefer the intervention of foreign security services in the UK to be on an extremely exceptional basis. Wouldn't you? I doubt Harry and Meghan''s security counts as one of those exceptions but it might and if it does and extends to this country then I expect the FBI and the UK to divvy up the bill.
I'm not their biggest fan but it's hard to deny that Harry, as a member of the Royal Family and a former serving member of the British Army of high profile, does face a credible risk and by extension so does his family. How high that risk is I don't know because I am not a member of the security services. But it's also hard to deny that as such the British taxpayer might have to fork out for him when he's in Britain if the Home Office is in the wrong. We'll have to wait and see.
.