The question about Current Tx Power

I find the wireless ap of ubnt can fix its TX power.

Why mikrotik can’t,like my hap lite,when I have adjusted the power to 19dbm,but the current tx power not all 19dbm,why?

BTW,What is the Tx Power value of “all rates fixed” mode range?
I can set it to 30 dbm,although it didn’t work as 30dbm ,but work as 19dbm.
p3.jpg
p2.jpg
p1.jpg

the other printscreen
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