Henry is letting people know that he is still playing Superman. He posted a promotional image of himself as the superhero and a video where he said he was back as Superman. He made a brief appearance in Black Adam, DC's latest movie, and there are reports that a sequel to Man of Steel is in the works.
The image and his appearance in Black Adam are just a small taste of what's to come. The caption states that people's patience will be rewarded.
There wasn't an official announcement that Cavill had given up the role of Superman despite years of rumors. We haven't seen Superman in a DC Extended Universe movie as much as we would have liked. As long as you don't count his role in the Justice League remake, the character's last appearance was a few seconds in 2019.
Man of Steel 2 or whatever it ends up being called, is still in very early development, with no directors or writers publicly attached. It is possible that he will show up in some of DC's films in the future, but for now, fans can hang onto the hope that he will do a good job.