Microsoft is releasing a new Fast Ring build for Windows 10 Insiders today, build 19018. Along with the usual what's new / what's changed / known issues announcements, it looks like the Windows Insider program is going back to more simple times. As of this build, the Skip Ahead Ring will cease to exist:
Starting today, Windows Insiders who have opted into Skip Ahead are being migrated back into the Fast ring. This means that Skip Ahead will no longer be reflected under Settings > Update & Security > Windows Insider Program. Going forward, we will not be offering Skip Ahead as an option for Insiders to sign-up for. Our goal is to provide everyone in the Fast ring the freshest builds at the same time.
The Windows Insider program has evolved over time, first adding the concept of Rings with Slow and Fast versions, and then adding a Skip Ahead Ring meant to be able to begin testing on the next cycle of Windows Updates while Fast Ring builds focused on tidying up the most recent cycle. After a time, though, with the jump ahead to 20H1 before 19H2 was announced or even acknowledged, things got a bit out of hand, and it sounds as though the program is harkening back to simpler times.
All Skip Ahead Insiders were moved back in with the Fast Ring for 20H1 some time ago, so it's not like Insiders will be displaced. If you want to continue to receive the latest and greatest Insider builds, stay in the Fast Ring. As of today, the Slow and Release Preview Rings, along with Fast Ring, remain unaffected.