Agreed. The hostility may not be as overtly violent by United Russia toward the KPRF as it was by the KMT (who committed actual massacres) toward the CPC, but there is nonetheless open aggression by the much larger and dominant ruling party against this smaller opposition party in the form of vote rigging, dirty political maneuvering, media warfare, arrests of its members, etc.

In my opinion a big part of why the "controlled opposition" accusation appeals to some western leftists is because they are not used to communist parties actually being a meaningful force in politics in their own countries. But to remain that the KPRF has to, for now, operate within the bounds of the bourgeois law.

We could argue about the validity of their choice to pursue an electoral strategy for now (though that is far from the only thing they do), but we have to remember that even Lenin said that whether or not to participate in a bourgeois parliament is not a matter of ideological dogma (always right or always wrong), but rather is determined by the present conditions.

From a dogmatic ultra-left perspective choosing anything other than "we need to do violent revolution right now!" will appear as "controlled opposition. To me, real controlled opposition looks like what the Bernie Sanders/AOC/Mamdani types are doing in the US.