These are related to @north python's leveling system.
There are several things that I thought about:
1️⃣ Global Boosters - There are currently 2x 24Hour XP Boosters out there that you can get from games. A global booster (with a very higher rarity) doubles the amount of XP of anyone that would send messages during its activation. Global boosters don't really last long though. (+ a command like /activeboosters)
2️⃣ Inventory Update - Currently the inventory has 8 slots, the only item you can get in there is the 2x 24Hour XP Booster, and it can be stacked. For example if you get 2 of these boosters, it still takes one slot of your inventory. Make this so boosters cannot be stacked. Following this, the total number of slots would remain 8, or even how it looks could be changed, to a Minecraft hotbar design maybe?
3️⃣ Booster Drops - If all slots are already full, if the user gets a booster from a game, it would fall off and break. If it's a global booster, it activates like usual. If it's a personal booster, then it would either: Activate for the people who sent a message in the past x minutes, or a message would pop up and ask people to click a button, and whoever clicks that in time, gets the booster. The strength of the booster would remain the same (X2 so it doubles your XP) but the time would be divided between the number of users who got it.
4️⃣ More Boosters - There's only one type of booster available at the moment (which is the 2x 24Hour XP Booster). The idea here is to have more booster, like a 3X one, with more rarity and less time, and as you can guess, 2X boosters with less time but more rarity.
5️⃣ Reward Command - Bring claiming your leveling reward to Discord from google forms. To prevent any mistakes, let the user change what they requested in the next 30 minutes. So when the command is executed, you get your requested cosmetic in 30 minutes, and you can change it meanwhile, before the 30mins timer runs out.