When the interface name is changed then all inteface is taken down so it means disconnecting all user from particular AP.
Could it be avoided ?

I think you can’t avoid this situation.
It is like when you change some configuration in wireless interface without using capsman, all the clients will be disassociated and then connect again. Wireless interface should check if all conditions are able to accept the clients again, even if the only change is the name of the interface.
Regards
Why they are dropped ? ROS knows that it is only name change. No other paramaters.
If I change Ethenet interface name then I do not see “link down/up” and dropping users from that interface. Why it is neccessary for WiFi ?
The issue is that wireless interface “firewall” name access-list and connection-list, are checked all the time you refresh some changes that’s why it have to drop all clients and then take it again.
In ethernet, firewall is a complete separate module.
Maybe you could ask for the new RouterOS feature or changes, don’t refresh all wireless client with all the interface details changes.