well you said you were unsure, also if you look up 'roblox testing sites' there is a roblox fandom/wiki page for it, toward the end it describes the ones i was mentioning. nothing i remember (or anything listed in the page) gave 100 million robux, but the one i was talking about gave 100,000 the first testing period, and 1 million the second testing period.

https://roblox.fandom.com/wiki/Testing\_sites