I would have been shocked if that hadn't been the case tbh.
It was obvious to everyone for at least the year before HMTQ died how much frailer she was, and became glaring from the death of Philip onwards. Her reduced appearances at the Plaitnum Jubilee just confirmed it. Charles became much more visible in that last year - he attended the State Opening of Parliament in her place.
As a PP said, it's pretty standard contingency planning.
If anything were to happen to Charles then obviously William would be Regent. In the case of George, then it definitely wouldn't be Harry, more likely a combination of Catherine, and selected Counsellors of State (Edward and Anne mainly I would imagine, if alive).
It wouldn't be Harry as he's now so far removed from the Palace (geographically & ideologically) it wouldn't be functional. It wouldn't be like previous Regency's with an underage King (am I right in thinking the last one is Edward VI?) The GBP would fully expect his Mother to be his Regent - not an estranged Uncle who lies overseas and whom he hasn't seen for years.
Hopefully, we will never have to witness another Regeny though, although it is an interesting discussion.