I like the simplicity of last/lobby.
Interesting idea not to put many ammo/health on second. It forces teams to give up position when they spam mindlessly, which is nice
https://i.imgur.com/nqJjSKV.jpg
At the moment that room looks super cramped. I'm afraid it's going to be nomans land until a team gets some sort of an advantage worth pushing on, and you'll end up with gameplay like sunshine where teams are 500m apart, as it's much easier to hold outside on mid/second.
Plus the only way around is from the side :
https://i.imgur.com/C3DQhLk.jpg
But then you're left in no mans land against enemies on high ground, so how about removing this ceiling :
https://i.imgur.com/ebOTcO0.png
At least soldiers would have an easier time going behind.
BTW giving scouts access to the rooftop on mid is too easy. You should remove crates and keep the rocks.
Middle looks like a go hard or go home situation. Either bomb or counter jump for the rooftop. Refreshing change from scout centric maps.
https://i.imgur.com/cPQp5IK.jpg
You may want to get rid of these little platforms that can make rocket splash bug.
Layout wise, if anything, maybe you should rework the room between 2nd and mid, and add a proper flanking route to lobby (like gullywash lower lobby door or something). I'm thinking of the left hand side from the attackers perspective, kind of like you did on last. This would probably improve pub gameplay too.