This is what I got from the user who saw a bug in emoji reactions: "You can register up to two emojis to send as reactions. For example: 😀😀 However, there appears to be a bug where you can register an unlimited number of certain emojis. For example: 🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️🙂‍↕️ My guess is that the latter are emojis that can be represented by combining two emojis into one. 🙂‍↕️ = 🙂 + ↕️ 🍋‍🟩 = 🍋 + 🟩" There are cases where it's possible to react with a sequence of 100s of emojis like one of the reactions in this note : Maybe it's not a bug but a feature? 🙈😅