this is FUD. Inventing another candidate while already sitting on already existing lists of tons of Navalny supporters? supporters to whom nothing happened through all that time? doesn't pass the smell check

Navalnyists are soft-banned in Russia. They can't make any meaningful public statements without hitting one of the censure laws (e.g. it's illegal to say anything about the war that differs from the official Kremlin line). The FSB just slaps the "foreign agent" designation onto the more loud ones and makes their lives difficult enough for them to migrate away. It's a slow cleanse but it's pretty effective.

You are talking about public discourse

I replied to comment claiming a candidate was invented by our gov to collect PII of people who signed for him. Until people who donated/signed for Navalny are in trouble I don't see why that can be true

There are tons of Navalny non-supporters who are latently opposed. Personally I'd say that they are actually more dangerous to the regime due to the stratum they represent. You just don't hear it on the internet because they are older and have shit to lose. Alexey was a youth's idol, not adults'. Many people never considered him a good politician, if mediocre. Maybe that other person wasn't "invented", but they definitely could use him as a trap. There's no way anything could change here through "elections".

I don't get, most who could get trapped by signing/donating to the new guy could already be via donating/signing for Navalny. Years passed and nothing

I've known him personally for quite a time and that's a ridiculous statement. He never was and isn't a revolutionary, but he always was pretty sincere in his beliefs and his attempts to fight in rapidly closing legal space.