On the Discord mobile app, sometimes I put in emojis via the window (not typing them, though that might not work either honestly) and seemingly at random times, when the message is sent, the emojis appear as ":emojiexample:" instead of the actual thing. I tried just editing the message and that does not fix it, so it has to be a new one it seems. I don't know if that's a known issue or if this is the right place to report it, but it's really irritating.
Edit (02.02.2022); The issue happens with emotes that have the same names, and it gets confused by capital letters. Thanks for everyone who responded, I'm still mad I never saw any input from someone at Discord itself, but hey... someday... Discord mobile will just stay poopie