There is. People are still demonstrating and organising, even in the knowledge that they risk arrest. I don't think you have shown any evidence for the idea the protests are small. Certainly from the reports I get from socialists in Russia, the idea that the demonstrations are small and that everyone participating is detained is not true. The demonstrations are both large and widespread; in the first weekend there were demonstrations in 58 cities. There is not widespread support for the war, which is very different to when Crimea was annexed and there clearly was popular support for that in Russia.
I totally understand that people will feel hopeless and that maybe there is no alternative but to just give Ukraine all the weapons they need. I don't fully agree but I can empathise.
However, I don't understand why you would attempt to dismiss the efforts of the left in Russia - who are used to being detained on demonstrations remember, it's not a new thing, they're used to defending themselves as well - as being of no consequence, based on no real evidence. That to me suggests something that is beyond simply feeling hopeless and wanting to do something or hope for something to end the conflict.