I could be wrong, but I don't believe TIBA is used these days as defined in AIP. When airspace is closed now due to controller shortages, the airspace becomes restrcited, or TRA. Someone not rated on the airspace will "manage" traffic, but I believe a clearance is still required (hence the charges), even though the level of service provided is not the same. Someone will be listening out for safety reasons, but don't expect much more.