The reason you apply sanctions is the same reason that you shoot at enemy conscripts in a war (despite them also being victims).

Except in the case of sanctions, you aren't even actively engaging in violence (which some moral systems would take issue with). You're simply choosing to not cooperate.

This. Plus sanctions are also a deterrent, and not using them when a state goes over the line will weaken soft power in the future. So while it sucks for Russians who don't support Putin it will make the Chinese or American or whoever is next to egregiously violate what the rest of the world considers right take the threat of sanctions more seriously.

Civilians in an authoritarian regime still have things they can do to undermine or weaken the regime without even taking any risks. They can not jojn any of the state institutions of repression - the police, army and security services. They can avoid doing business with such people or organisations as far as possible. They can seek out independent information, and disseminate it through family and friends. They can peacefully protest if it's safe, or in some cases vote or abstain from voting.

They can of course go much further than any of this, but we need to make it clear how we feel about their regime and it's actions. We need to provide a motivation to resist. Yes it sucks, the Russian people are not our enemies, I know and work with Russians, including close colleagues. Sanctioning the Russian state, and struggling against it from within are two sides of the same coin. It sucks that anyone has to do any of it, but that's the fight we're in whether we chose it or not.

How about the civilians in Ukraine who have to cower in basements, watch their loved ones die, and flee the the country leaving their entire lives behind? The children in Ukraine who have to live through a traumatic war losing all of the stability that they have?

The suffering of Russian civilians is nothing compared to what is happening to civilians in Ukraine.

One person suffering is not a good reason to go cause some other person who isn't at fault to suffer.

Comparing suffering is useless. There is no objective measure for pain, just as diminishing the suffering of Ukrainians because Yemen or Palestine is pointless.

Some brave Russian people are now suffering in Putin's prisons for speaking out against war. Some mothers will never know how or where their children died. Some African students in Ukraine are suffering from racism perpetrated by other war victims.

It's all bad and they all deserve compassion.