Black holes embedded in FLRW cosmologies

Abstract: There has recently been some considerable interest expressed in a highly speculative model of black hole evolution -- allegedly by a postulated direct coupling between black holes and cosmological expansion independently of accretion or mergers. We wish to make several cautionary comments in this regard -- at least three exact solutions corresponding to black holes embedded in a FLRW background are known, (Kottler, McVittie, Kerr-de Sitter), and they show no hint of this claimed effect -- thereby implying that this claimed effect (if it exists at all) is certainly nowhere near ubiquitous.