The problem is that one can believe (I do) that there should be an independent Palestinean state while also recognising that the relationship between Palestine (particularly Gaza) and Israel is nothing like Ukraine and Russia.
Ukraine is a democratic country that posed no threat to the security of Russia. Its freedom can be universally celebrated without reservation because its existence poses no harm to any other country.
Palestine, as 'led' by Hamas, does pose a security threat to Israel. And so simply calling for a 'Free Palestine' in the current context is not even slightly comparable to Ukraine. A free Palestine under Hamas means a free country neighbouring Israel that is committed to eradicating the existence of Israel, and is willing to take any steps it can to achieve that (such as the activity we saw on 7 Oct).
Like it or not - 'Free Palestine' right now does mean freedom for Hamas to continue its approach. At a time when anti-semitism is on the rise, an agent for TFL leading chants that could reasonably be perceived as an endorsement of the 'river to the sea' approach of Hamas is wildly inappropriate.
None of that means that Israel's approach has been the right one, either before or after 7/10. None of it means that a two state solution isn't the ideal outcome.