Developers can now download and test iOS 12.4 beta 2, released this morning, build 16G5027i. No other software betas received second betas today (yet).
The release comes five days after the first developer release of iOS 12.4, which did not contain any new features. Many have cited how the update is expected to support Apple Card for users in the United States.
Apple normally releases developer betas in 7-day intervals, but these short turnaround times for betas may indicate minor bug fixes and performance and security updates, ahead of WWDC set to kick off in June.