Steam is very bad about verifying game updates, which allows them to publish faster than other platforms sometimes. By which I mean that 90% of updates to games never get checked, just pushed live without any steps to ensure they meet the standards Valve require when you're uploading a game. Inserting malware is hard on a game's launch, but stupidly easy once the game is live. So seeing a game getting updated on Steam first is pretty normal. It's also a bigger platform, so a lot of devs prioritise it over other storefronts.
Hopefully, this doesn't take too long to get updated, though.