Isekai Maou to Shoukan Shoujo no Dorei Majutsu - Ch. 99.1

[MangaDex]

 

[Kaarme]

Yes, I'd say Modinaram's ego got so diluted that perhaps the intelligence itself dropped considerably. That being said, it's possible that if all the pieces of demon lords get fused, the original demon lord would be reborn instantly. Or perhaps Modinaram can build a new, stronger ego if enough time is given, even without all the pieces.