It would depend on the geo-political context, currently there are less viable options.

In a different context, beyond the main mass of hardcore criminal (several million russian) that require strict punishments, you could leverage a legal proof method.

Every russian signs a legal paper outlining and their overall support for genocidal imperialism, putin, knowingly promoting false russian propaganda and so on.

Based on the of level severity of their support for genocidal imperialism, they would have to pay financial compensation and engage in global community service work (de-mining in Syria, junior janitor in an infectious disease hospital in rural Africa).

The legal paper would have a clause stating that if you claim you never supported genocidal imperialism (as certified in the legal paper), but later evidence comes up that you were actually supportive of russian degeneracy, you lose all your assets and will be required to do two decade of global community service (or go to jail). This clause would be valid indefinitely for the life of the person.

Note, I am not saying the above-mentioned approach is viable right now. I am trying to show that there methods to create incentives for russians to be open about their support for genocidal imperialism.