Greetings

I would like to ask why it's no longer possible to run DHCP client on interface that is bridged? It was possible in older versions, was handy sometimes and never created any problems.

It is not possible in newer versions because is a bugfix

There is no reason to have a DHCP server in a interface that is bridged with another, layer 3 have to be set it in Bridge interface only , because all the interface bridged are joined or "slave" what happen in the bridge.

I know sometimes we need this kind of special things but mikrotik helps us fixing possible mismatch configuration problems.

Once an interface is in a bridge you should disregard the interface and use the bridge.

In most cases, DHCP client on bridged interface is miscofiguration. But it was also interesting hack that allowed to get two IP addresses from DHCP server on one physical interface. I don't know if it could be useful also for something else. Unfortunately for those who used it, MikroTik decided to prefer proper configuration and disallowed this use. Too bad they didn't provide proper replacement (virtual interfaces) first.

DHCP Client on a slave interface also was very useful to trigger a DHCP renew on interface up/down event. This is necessary in various ARP-Guard/Dhcp-snooping situations.

This no longer is possible with the DHCP Client on the bridge.

DHCP client on bridged interface
I want fully transparent bridged network where DHCP client will be on WLAN1, but i also want mngmt IP(lets asumme that mngmt IP's are given by DHCP server) to be reachable from ETH, so bridging the two interfaces is easiest thing right? Mode will be station-wds.

I got 2 interface bridged in 6.39.1 and i got ip from DHCP , but ROS given "moving client wlan1 from slave to master port bridge1" what is that excatlly? could it be "port number" in bridge port/status ?
Because WLAN1 is alrdy root port in that bridge