It seems that it was just news that was blown out by the media or the fans of Sadio Mane because seeing that the career of his favorite player was not so bright there, they felt like they wanted to reminisce about Sadio Mane's success at Liverpool, even if he remained at LFC it would probably remain the same because he long enough injured before the World Cup to keep him out of action for a while so that will also affect LFC.
Sadio Mane moving from Liverpool was his own wish at the time, so I don't think Liverpool nor Mane himself intends to reunite, and I don't know if any Liverpool players have ever left the club and come back? to my knowledge there never was, but if there is and he does come back, maybe he will shine again or be able to compete with other players in the same position because there are Gakpo who can also play in other positions, Diogo Jota and Luiz Diaz, so it looks like we have to stop with speculation Mane will return to his old club Liverpool, because next season will certainly be different in results.