Maybe my memory is a bit flawed but did this guy:

https://mikrotik.com/product/RBmAP2nD

always have 650 mhz cpu since the very first day it came out?

Actually MikroTik boards are so good, they have to put one or two electrolytic capacitors over night, to make them a bit crappy so they don't just obliterate the competitors.
It's out of pity.

No I'm serious xD. I even found some old website that says it's 400mhz. So that I wonder what was previous cpu in this thing (if my theory is correct). Original mAP is quite old router, significantly older than hAP, hAP lite, mAP lite, hAP ac etc.

This is the RBmAP2nD, the previous model was the RBmAP2n. It had single chain wireless and a 400MHz CPU.

Look this:
viewtopic.php?f=3&t=77535&p=549638&hili ... et#p549638

The good news is that the product has been discontinued ...