The downside of course is you will have to pay a fee and even if their service is paid there is no guarantee that the investigation will turn out well and they will recover your funds.
It's literally on their front page and you don't have to scroll too far: "We do not charge an initial fee, the success fee is counted from recovered assets."
If they were proposing to do it any other way no one would trust them.
Oops, I might have misread this part
"GET APPROVAL We will present your estimated fee once the case is approved"
of their presentation. But then again I would still like to see their previous cases especially their recovery rate to see if this is worth trying out or would it be just another waste of time and keep my hopes up for nothing. Yes a small cut would seem to be a no brainer if you want to recover most of your crypto but how long will it take or how long the process will be before they start doing their investigation, still this kind of service has no guarantee or even if they will accept your case in the first place.