levels reverting bug

[Ben]

So I was doing the vision of the future challenge and noticed my level kept dropping.
here I am at level 89 using a level 90 spell:

https://cdn.discordapp.com/attachments/508364203325915166/543139740816506900/unknown.png

[Jey]

Not a bug.
You desequipped True Sorcery, thus you lost its bonus to XP and one level.

[Ben]

Nowhere in the spell description does it say it alters current experience or level, it says "increases character experience gained from sources by 100%".

[Jey]

Character experience is not "earned" in the common sense.
Doing an action or buying a source doesn't give you an amount of XP.
Instead your total amount of active actions and sources goes through a formula (you can find it on the wiki) and it makes you have a certain amount of XP.

Therefore every character XP modifier be it upgrades, attribute perks, spells or items automatically increases (or decreases) your current XP.

It also means Hungerer, who eats sources, eats your XP (and you will regain that XP by buying sources/having them bought by a pet).

In your case, removing TS removes the bonus and decrease your character XP.