Forgive me if this was already suggested but I couldn't find it while searching for it.
The API doesn't have an endpoint for adding multiple reactions at once. However, there is an endpoint for deleting multiple reactions. I believe that this was probably not implemented to rate limit the selfbots from bombarding the message with a huge list of reactions. But when it comes to a normal bot that clearly follows the Discord ToS and the ratelimits, they should be allowed to add multiple reactions at once. This doesn't let the users see the bot adding the reactions and makes it visually more appealing.
To further enhance this, there could be a Channel Endpoint which accepts a prepared Message Object as the form-data. In this case, I can prepare my message with a set of reactions and send it to the endpoint in one go.
This will be far more visually appealing (and probably performance efficient too) than sending a message and then adding a reaction to it one by one.
We will reducing the number of requests from (N + 1) to 1, where N is the number of reactions.
Kindly consider this suggestion and if it isn't possible to implement this for any reason, please let me know.