According to multiple sources, Ray Park was slated to return as Darth Maul for the Kenobi series, before it was rewritten to feature Darth Vader, instead.
In early 2020, there were
repots production on the series came to a halt, in order for some rewrites to take place. Sources say Filoni and Favreau thought the story was too close to that of
The Mandalorian. At that point, Park was said to be preparing to play Maul. although,"
A Lucasfilm source contradicted the account, saying Maul was never intended to return for the series."
With the rewrites;, if the sources are to be believed, Maul was out, Vader and the Inquisitors were brought in.
(Source:
THR)
Personally, if the Maul story is true, I'm glad it was changed; it feels like it would've been a massive rehash, if not retcon, of the storyline from
The Clone Wars and
Rebels. Unlike the 'end credit scene from
Solo, how much time would be needed to explain Maul's journey from the end of ,i>The Phantom Menace?