WAN serving DHCP addresses on eth1

RouterOS Beginner Basics
1

Here I am using a RB5009UG+S+IN. Used the Getting Started configuration in documentation pages.

After configuring DHCP server on the bridge named local, I am seeing DHCP addresses served on the ether1 WAN interface.

Any idea how to prevent this?

2

Remove ether1 from bridge local?
Without configuration export this is the only guess.
/export file=anyfilename hide-sensitive
Remove from exported config public IPs, MAC addresses, passwords and other sensitive info, and post here between code tags