We were frequent Royal cruisers until recent years, but service and food quality issues (before Covid), pushed us to Celebrity. We first sailed on Celebrity on the Millennium in September 2022, and experienced great service and food and an upgraded feel.
I don't believe that just because RCI does something means that X will. Take the chocolates on the pillow for example. They've been long gone from Royal since ~2009, but that change hasn't reached Celebrity, for example. So I'm hopeful 2x a day housekeeping is the same way.
Royal isn't marketing itself as a "luxury" line, so its easier for them to reduce housekeeping service. Hopefully Celebrity sticks to the their "Luxury" marketing and actually carries that out without a reduction in housekeeping services.