Every civilians wear these can be killed legally. So, it works both ways. But chances are as thing get brutal (look up Grozny), they will be killed. A lot of people simply dont understand the consequence of this "good intention" assistance.
And while soldiers and combatants are legitimate targets in general, this war is not legitimate. It is a war of agression against a sovereign country, so you cannot really claim that killing soldiers is simply legal here. The responsibility for all the death and suffering caused here lies with Putin who commanded this invasion.
But as Russia is bombarding cities with civilians already, and it is likely they will escalate these bombardments even further, you are anyway in very real danger of getting killed as a civilian.