No it isn't.
This is nothing but A LIE CACS tell
Namor isn't an actual Black Panther villain
Black Panther vs Namor was one story. It's never been this decades long Batman/Joker or Lex/Superman shyt like how YOU CACS like to spin it
The only people who wanted Namor in the black panther sequel were CACS because they thought the character would be cast a cac and wanted that an audience surrogate for them in a Black Panther 2/black cast movie. Along with seeing an advanced black nation, that is written as being stronger than any other, get partly destroyed. Which is a b*stardization of the concept of "Wakanda" in the first place as it's meant to be indestructible to OUTSIDERS. It was ONLY done in the comic to placate RACIST Cacs.
Did this cac just say Black Panther fans wanted to see the storyline where the most advanced black nation in the Marvel world gets flooded?