isolated reaction issue

I'm having issues reacting to specific users. Every time I add a reaction to messages from these two specific users, it quickly removes my reaction, and it doesn't matter whether the reaction is one I add myself, or if I'm adding another number onto others' reactions. This issue only occurs with reacting to two specific users' messages, regardless of the server I react to them in. Is there a fix for this, or is this a bug that needs fixing?