that was still from leo's timeline?! i thought it was a sort of multiverse thing and it happened recently. though i guess it doesn't matter much because the absolutians jump around the timeline.
At the start of Regulos Ep 1 we see Leo and Regulos sparring. After that, Leo's planet got invaded by the Magmas and that's where Leo's show started. The one who got beaten up like a punching bag by one of the Magmas is Leo's brother Astra (which he managed to re-unite with Leo midway in Leo's show).
Man so Regulos was chained up for a very long time, from Leo's timeline to the latest Heisei/Reiwa Ultra xD
though i guess it doesn't matter much because the absolutians jump around the timeline.