RAW Underground was introduced in a bid to increase interest in the show as ratings continue to fall. It didn't really make much difference, but did generate a lot of chatter online and gave the diehard fans still tuning in each week something to look forward to that was definitely a new idea from WWE.
Now, it seems that the weekly segment - which has been absent from RAW for the past few weeks - is done.
According to Dave Meltzer in the latest Wrestling Observer Newsletter, WWE made the decision to scrap RAW Underground a few weeks back. Why? Well, it's because of the COVID outbreak that broke out in the WWE Performance Center and caused chaos in NXT and (to a lesser extent) on the main roster.
This likely means that Shane McMahon is done with the company again for now, and the writing was really on the wall when Dabba-Kato and Arturo Ruas were drafted to RAW. Meltzer notes that there was concern in WWE that bringing all that talent back could to another COVID-19 outbreak.
If nothing else, these segments did freshen up a few Superstars and introduce fans to some new names, so it now remains to be seen how they're used on the main roster.