20% of users (dev's words on hearings) is substantial.
There is a caveat that Dojo wasn't around from day one. So it may be 20% of users at the moment of their arrest.
It is not 100% clear if FEDs could access collected XPUBs of Samourai Wallet users, but it was mentioned on the hearings and developers reported about 20% of users that were using Whirpool coordinators.
This refers to the shut down Samourai Whirlpool.
But the coordinators listed on https://liquisabi.com/ use the WabiSabi protocol used by Wasabi Wallet which does not share the users xpub.
However, the BlocSci tool has a collection of known WabiSabi flaws when it comes to chain analysis. Albeit I am personally do not consider it as flawed protocol unlikely to JoinMarket for which my own analysis indicates that Fidelity bonds are ineffective and there is high likability that the orderbook is full of Sybills.