Specify a default emoji font
In addition to https://bugs.kde.org/show_bug.cgi?id=424090
Plasma comes with a preset of default fonts like Hack and Noto Sans. It should do the same for Emoji fonts.
Plasma had a default set of emoticons before that was nuked in !52 (merged)
We do that for Hack and Noto Sans anyway, so it's not unprecedented.
Linux distributions (openSUSE comes to mind) ship with broken Emoji support since years and seem not to care.
My personal suggestion for an Emoji font default would be Twitter's Twemoji because it looks rather complimentary to Breeze, the designs follow those set by WhatsApp, Samsung, and Apple (the latter's also used by Telegram by default), and freely licensed. Popular services like Discord and Roblox default to Twemoji.
Noto Emoji are also open source but the design is rather uncommon in the eyes of users because few Android phones default to it (most notably Samsung). The color palette is also not complementing Breeze that much.
OpenMoji is free but the color palette doesn't complement Breeze IMO.