As already stated the map is just too open. Especially the long wide corridors are a pain to travel while holding the flag. In fact you should try to make the map much smaller. At the moment it almost consists of corridors which dont offer much possibilities for escaping nor fighting.
Another thing is the PU placement. 2 haste and 1 quad are way over the top. Switch the hastes to regens and make the quad alternating with haste or get rid of the latter and only provide the two hastes (maybe alternating with quad).
Another thing which really annoyed me was the midfield. It reminds me of some doom maps with its cramped design and high obstacle walls. You should maybe rethink this part and make give it one more level to make it more interesting. Also it should be less confusing as it is often the last possibility to stop the enemy flag carrier. So you should not get lost while searching for him in midfield

Also the distance between the middle section and the bases should be shortened drastically.
The base itself seems interesting but too easy to defend. Two defenders with YA and RA around the corner will be impossible to resist not to mention to kill. Maybe some jumppads (are there any at all?) would improve the connectivity and overall speed. Especially in base there should be some alternate routes to the flags than just one staircase for each of the three routes.