According to Nasa.gov:
Details: Ocean planets are long imagined but difficult to confirm, and TOI-1452 b is no different. About 70% larger than Earth, and roughly five times as massive, its density could be consistent with having a very deep ocean. But more follow-up will be needed. The planet also might be a huge rock, with little or no atmosphere. It could even be a rocky planet with an atmosphere of hydrogen and helium.
The new super-earth is said to have a density that is "consistent with having a very deep ocean". What does this mean and how is this calculated? The article unfortunately provides no more details as more information is needed to be gathered from the planet.