First thing I noticed is how incredibly cramped the spawn room feels, I can't really imagine having 5+ other players in there as well.
Personally I love the idea of stupid hiding spots but this is a bit much even for me, this already already seems kinda strange since there's next to no benefit of taking this door out of spawn.
Should clip over the inset on the window and remove collision on the door frame since neither really provide anything besides a place to get stuck on when you get bounced. I would also suggest clipping over the entire ceiling to prevent players from getting caught on the support beams.
Would suggest making the props on the wall nonsolid unless you intend to have them as a hiding spot. Right now if you were on those boxes for any reason it'd be very easy to get caught on them.
Unless you plan to have players using the railing to dodge on I would just clip them off to prevent people getting stuck on them since the prop collision is kinda bad.
This area feels really cramped as well and I don't really understand the point of the horizontal bars since they really only seem to get in the way of jumping. Also the roof clipping is frustrating as you'll often get caught on it while jumping. Would also suggest making the displacement ground at the top of the stairs a bit smoother and potentially making it non solid.
I don't think that any of the props in here benefit from being solid unless you want them as (shitty) hiding spots. I would also probably slightly rework the geometry on the right as the area where the manhole cover is doesn't seem to be being used for anything.
Should clip/bulletblock this little lip to prevent splash bugs and probably make the pipes in the corner nonsolid.
If you're going to have one of these be solid you should probably make sure both of them or none of them are solid as having inconsistency with prop solidity is pretty annoying.
I think you should smooth out the upper part of these displacements so they're more consistent for jumping. Right now when I try to rocket off them it seems pretty bad (Combination of awkward geometry with the displacement itself and the clipping)
Examples of the clipping as mentioned above
As mentioned before I would highly recommend changing how you clip off roofs since having hard edges at the top like this makes jumping feel awful.
This sightline is pretty absurd as you can basically look at all 4 ways that you get to mid from one location. Getting rid of this will be pretty difficult and right now I don't really have any suggestions for fixing it.
Personally I don't think that large health or ammo kits should ever be used in a serious map considering how important health and ammo management is in TF2. Besides that you already have 3 medium ammo packs on each side of mid that are incredibly easy to get to. I think removing this and moving the health pack here could be a good option. Also some kind of seam thing on the displacement right next to the blue timer on my hud.
This little nook looks really nice but since I don't imagine it will ever be used for gameplay I would suggest moving it forward slightly and then clipping it off so players don't get stuck on it.
Same deal as before with clipping/bulletblocking the inset area to prevent splash bugs
Right now I see middle as the biggest problem since you don't really have any defined flank routes and the entire area is just super open. There's also a lot of perch spots for soldiers and potentially demos to go stand on and those typically aren't very interesting fights. There's also the big issue of that mega sightline that would also double as a pretty strong area to forward hold as you'll be covering 2/3 spawn doors with height advantage and you could easily have a roamer watch the far side since you'd be forced into a small tunnel anyway. Currently I don't really have suggestions for any of those problems but I think that they're worth bringing up sooner versus later, however I could be totally wrong and it could play out fine.