The last mixer I saw that claimed to use coinjoin, didn't use coinjoin. In this case, I see many red flags: despite being a brand new website, they claim to be able to coinjoin 100 Bitcoin. Doing that would require several other users to coinjoin the same amount at the same time, which isn't realistic.
@OP: can you sign a message proving ownership of anything close to 100 Bitcoin? My gut feeling tells me the most likely scenario after someone depositsi 100 Bitcoin is an an exit scam. And it'll happen at much lower amounts too.
You should know that bitcoin transactions on the blockchain are far from secure
Did you come up with this BS on your own?