ridicule root is the name

Dubious Depths

It's a shame Sega didn't add this in the 2011 version This is what a Last level boss looks like instead that crazy fan boss.

@NotMGM64 The only indications we have for what it looked like are pieces of concept art with one showing a Marble Zone-esque level with rainbow waterfalls. That and a clip of the ending shows Sonic dodging an antlion Badnik.

Actually, I believe Desert Dazzle was gonna take place between Quartz Quadrant and Wacky Workbench. R2 is Relic Ruins Zone, a cut stage from the original Sonic CD.

What if they used this in Sonic Mania?

R9 stands for Round 9, basically. Pretty much as a means to keep things organized so that the level designers don't forget what goes where. and given the context, R2 was gonna be Desert Dazzle.

I wonder if we get the sonic 2 digizer image badniks with full shading soon

...Or the R would stand for robotnik....Robotnik-9

The levels folders in the disc of the original Sonic CD were labled as "R-(Number)"
R-9 for the scrapped boss-only level and R-2 for the scrapped second level.
Both levels weren't in the original disc either due to time constraints back in 1993.
Taxman wanted to add them in the 2011 version, but got vetoed by Sega.
An update accidentally put them back in their incomplete condition.
Fortunately, DarkVampireDee made a full tileset for Desert Dazzle which you can download on his Deviantart page. While I decided to remake the bosses intended for the levels. I even used concept art as a reference for the unicycle boss's main weapon.

R-9? What does that mean?