No, why? Does Trezor wallets are less secure because software sources are available? Does SHA algorithms are less reliable because they are known? You overestimate things just because you do not know how they work. Everyone knows how cars are build, but still some do it better.
The problem is, you are trying to compare services like Trezor wallet or car building to a service that is considered an "enemy" of different states because they are making it harder for them to snoop people's transactions.
I do not expect to know every address managed by mixer,
But your Government would be very glad to know this.
By making the algorithm open source. You as a customer are not the only one looking at it. Some overzealous Government agencies will that want to uncover your transaction trail will even use it more than you and crack the puzzle open.
Don't you think privacy is heightened when there is mystery around it? Even the Chainalysis services won't know where to start, at least.
Really, it is not about stealing know-how, as you must enough resources to run service like that and average person cannot do that.
The average person is not a threat, you know who the threat is, and they have all the resources at their disposal if they decide to go for a witch hunt.