The former Eintracht Frankfurt manager left the Ligue 1 club by mutual consent last month despite overseeing some notable victories.
Toppmoller guided Lens past Paris Saint-Germain in the Trophee des Champions and also masterminded a UEFA Champions League win over Slavia Prague.
However, the club managed just one victory from four Ligue 1 matches under him, leaving the club 10th in the standings.
Lens attributed his departure to differences over the club’s restructuring plans, with Toppmoller and the hierarchy reportedly holding contrasting visions.
“To find yourself confronted by the fact that, if your assistant remained an assistant, you yourself were sacked, was a blow,” Toppmoller told Spielmacher von 360Media (via L’Équipe) podcast.
He also described his exit as “a big disappointment and a shock” and added that he was “stunned” while describing Morgado as “too demanding, too loud, (and) in conflict with too many people.”