BuddyPress.org

If you need to stay on BP 1.2.4, you could probably just copy the part of the bp_core_fetch_avatar() function that adds support for the ‘html’ parameter… but I’d strongly suggest upgrading when you have the chance.

See the codex article on upgrading:
https://codex.buddypress.org/buddypress-site-administration/upgrading-buddypress/