Flashes, I think? I’m just recalling screen shots from a few weeks ago, could definitely be wrong, but there are a few popular alternate clients now.

That seems to be the most popular indeed, but it's not a normal client, it's a niche client that only displays photos and videos apparently (?) by filtering them from the official Bluesky thing, and it has 263 ratings on the App Store. The other one I saw mentioned in multiple places is GraySky, which seems to be a fork of the official client with some modifications, it has 63 ratings.