Popeye's an interesting one because I had thought he'd be one of those characters screwed over by the whole "the copyright expired, so he's public domain, but certain aspects of the character are still trademarked which limits his use" thing, but...apparently that's FAR less of an issue.
The basic rundown for those who aren't aware is that the Popeye character is owned by King Syndicate, which is owned by Hearst Holdings, Inc. (yes, that Hearst), while WB currently owns the animated shorts through Turner Entertainment (the same subsidiary that gives them access to the pre-1980s MGM library). Popeye himself enters the public domain in the US next year, so WB would have major control for something like Multiversus...but the trademark would still persist and be kept by King Syndicate/Hearst Holdings, and Hearst has been very good at trademarking the character name for everything under the sun, and keeping said trademark up.
HOWEVER.
The one area they let the trademark lapse? Video games. The trademark for the use of the name Popeye in video games lapsed in 2009. So once 2025 rolls around (and let's be real, he was never going to be one of the two characters immediately after Nubia in October lmao), there shouldn't be any issues with including Popeye provided he's based on the animated shorts instead of the newspaper comics.