So, after doing the Battle Quests I was spending the Exp I had just earned, and when I had around 800 left, I clicked 'Speed (750 EXP)'. Instead of going back to that page, it showed the 'Subeta is down!' one. I clicked F5 as I usually do and it shows the following:
Lusitano -655 EXP Points
Did it buy Speed 2 times? I really don't know because I never keep track of how my stats are. Has this ever happened to someone else? I'm not sure where to create this thread (Battle, Help & Questions, Problems & Bugs) so I'll just leave it here...