As far as I can tell, the longtime Second Guest Stays Free Honors benefit has been dropped, as of the 2023 terms for the program. This is not a surprise, as Hilton stopped touting the benefit over the last year or two. Also, in the US, single travelers have been booking double occupancy to get double F&B credit, so perhaps Hilton is looking at charging for the 2nd occupant to help recoup F&B credits.
The following language is in the terms I pulled up today with a 2023 date:
2nd Guest Stays Free: A quest stays free in the Member's room on qualifying stays at hotels when there are additional charges for double occupancy. This benefit excludes stays at any hotel when the rate includes additional components (e.g., meals, activities, parking); specialized rates (e.g. package rates, bed & breakfast rates) or taxes that are quoted as a per person or per room charge; or is an All-Inclusive property.
Late Check-Out: Must be requested …..
Some places may have a per person (per night or per stay) occupancy tax, and that technically gives Hilton properties an out from this benefit even as that language is probably being used to collect the additional guest occupancy taxes rather than to increase the room rate to a double occupancy rate during the stay initially booked as a single occupancy rate.