This bug occurs because the removed quirk slot is still occupied by the red glow. This appears to be an oversight by the team because the glow is supposed to dissipate after a few seconds, in which case it does not.
One temporary solution I found was to save and reload your game after you remove a quirk with the potion. Upon reloading the save, the red glow will no longer be around the empty slot and will be free to take in another.
In my case I wanted to remove the no-touching quirk
With the red glow gone, is the no-touching quirk truely removed? Based on people's report, I don't think so, but I will give it a try
I don't think it will truly be removed 100% of the time. The red glow unlocking 5+ slots and the quirks which leave traces after their removal appears to be two different problems.
Quirks are, to my knowledge, never properly removed by the Quirk-B-Gone potion. They might not appear in the quirk panel, but they will still be active.
When you consider that Vampires suffer from a similar problem, this makes sense - if a similar system is in use, it will suffer from the same problem.
