My Discourse emojis don't work when I change my Discourse domain

Product Support
2

If you don’t know my mean, I can give you an example.

—Before I change my Discourse domain—

Old Domain: forum(dot)example(dot)com
Emoji picture URL: forum(dot)example(dot)com/happy.png

—After I change my Discourse domain—

New Domain: bbs(dot)example(dot)com
Emoji picture URL: forum(dot)example(dot)com/happy.png