No, I don’t have the wrong number. Apple launched this afternoon on macOS Big Sur 11.4 first beta, even if version 11.3 is still in the preliminary phase (the Release Candidate version was released yesterday, after the event). If you are part of the Apple Developer Program, you can download this beta as if it were another stable update.
Keeping in mind that we will be seeing some important news in macOS Big Sur 11.3, version 11.4 it may be a version with less detail. Either way, we have to wait for the experts to research the source code of the new beta for surprises, which may still exist.
Latest development releases before WWDC21
macOS 11.4 this may be the latest relevant macOS Big Sur update before seeing macOS 12, the successor to Big Sur, unveiled at WWDC21. We don’t know if this will be tied to more hardware news, although there aren’t any rumors to back it up. We may have minor news in some departments.
If you are not a programmer we do not recommend installing this beta version: it is an unstable version and intended to be tested by an expert. The best thing to do is to wait to download the final and stable version of macOS Big Sur 11.4 as soon as it is available.