1. He was unlucky enough to be cast as Superman in movies directed by a guy who wanted Superman to be a dour, cranky, scary monster, none of which are Cavill's strengths in terms of performance.
2. The Snyder movies unfortunately created an image that casting directors and marketing departments still insist on using for him as a big muscly dude staring you down on the poster.
3. Cavill has had enough leading roles in enough different movies that it's very clear he simply isn't an opening weekend draw for the mass audience.
4. Even if he could open a movie strong, we are in an era of movies where movie stars don't sell tickets. People don't go to see a movie because a particular actor is in it, they go to see it if they're interested in the movie's premise, IP, or story. This is why The Fall Guy, packed with stars including an Oscar nominee from this year, barely made a dent while Kingdom of the Planet of the Apes, which has no recognizable stars in it, is doing gangbusters. See also Godzilla x Kong.
Combine all that together and you've got a real bad situation for Henry Cavill. If I were his agent (and he hopefully has gotten a better agent in the last year or two, especially after Argylle), I'd be pushing for him to be in supporting roles and encouraging him to focus hard on making that Warhammer show a possible Fallout style breakout hit.
