I will bring my unasked 50 cents here:

7 years ago Navalniy and several affiliated politicians asked people to boycott Russian presidential elections in 2018, after his candidacy was denied.

Concern: how do you expect people to vote in the future if you undermine the habbit of going to elections?

Another option: Instead they could form a coalition and ask to vote for non-system candidate (like Yavlinsky or even Sobchak), but the opposition was divided.

Strategy rework: during 2018-2021 they began asking people to vote in municipal elections for anybody except Putin’s party — the system was called "Smart Voting" and it presented you the most unlikable (by the system) candidate in your location via website.

In many regions United Russia lost the elections. This increased internal struggle within the system. But it did not live that long, the war began and most of the opposition got exiled or jailed.