Posting anti-war, and therefore anti-government / anti-state sentiment on a platform essentially monitored and run by an authoritarian regime seems like the least likely form of protest you will see, as firstly it's most likely to be censored, secondly it's the easiest way to oust yourself to the authorities, and thirdly even if posted securely will be simply seen to be a weak protest/bot.
My wife is Russian and quite a lot of my friends and obviously relatives are Russian. All are against the war (that I know of), and were so before mobilisation.
It's true to say mobilisation has made people more concerned, but hardly fair to claim that people supported the war before. Of those who aren't anti-war, I'd take a guess that most fall into a neutral camp where they're trying to continue living their life as normally as possible knowing that realistically there isn't much they can do to stop the war that won't involve destroying the rest of their life with no impact on Putin's regime.
The consequences of opposing the war have always been abysmal in Russia. Anti-war sentiment online or in person can come with a 15 year prison sentence. Rape and assault are incredibly common in Russian prisons and the likelihood of returning to normal life is very slim as many Russian firms don't touch ex-convicts.
Quite often people quote a Levada Center poll suggesting 70% of Russians support the war/government position, but usually omits how many refused to answer the poll. These pollsters call you and ask if you'd like to answer questions about Putin / government / war, at which point most people hang up because in the moment they don't know if the Levada Center is independent/government controlled. The very few polls that are concluded will mostly lean to people that support (or outwardly pretend to support) the government, which is hardly a fair metric for judging opinion. The alleged 30% who went through with the poll and answered negatively about the government are braver than I'd ever be. I'd hang up.
The only real way to gauge Russian opinion is to befriend and converse with them behind a closed door. I know it's anecdotal again, but in my many travels to Russia, most people express anti-government views behind closed doors, and this most likely extends to the war.
I think in the West we're too quick to demand people in more repressed states do more to protest. A common statement I've heard the past few months (especially in relation to my wife, family and friends) is why they don't protest, why they don't overthrow Putin's regime. The consequences of doing any of that are so much higher, and if the positions were swapped I can hardly see Western citizens doing what they demand the Russians do.