Font Bars and Negative MP

[BLORTH]

I went to rejuv some pets on a font (Juggling Quagmire) that has 9 bars against my Lich. I was under 10 MP, but wanted to see what would happen anyways. When I rejuv'd, my remaining MP was taken and 1 MP was taken off of the Font. Using Rejuv again was successful, kept me at 0 MP, and drew 1 MP from the font while still returning the same message that I was taxed by 9 MP from resistance at the Font. In essence I am able to rejuv for 1 AP/1 Font MP which I don't think anyone intended.

EDIT:
Tested again with 4 MP.
- You feel magical resistance to your connection with Juggling Quagmire cause you to use 9 MP from your personal mana reserves. (2022-02-14 12:04:40).
- Kwazirr drew 1 Magic Points from Juggling Quagmire. (2022-02-14 12:04:40).
- Your pet, Wassail (a Ghoul), has been rejuvenated. You spent 10 Magic Points. (2022-02-14 12:04:40).

Result: Rejuv successful, 1 MP drawn from Font, I remain at 4 MP.

- You feel magical resistance to your connection with Juggling Quagmire cause you to use 9 MP from your personal mana reserves. (2022-02-14 12:30:06).
- Kwazirr drew 16 Magic Points from Juggling Quagmire. (2022-02-14 12:30:06).
- Your pet, Kael (a Necrophage), has been rejuvenated. You spent 25 Magic Points. (2022-02-14 12:30:06).

Result: Rejuv successful, 16 MP drawn from Font, I remain at 4 MP.

[BLORTH]

Bumping this because it's still happening on the same font.

Observed on Kwazirr.

I am at 6 MP. Font is at 32 MP.

- You feel magical resistance to your connection with Juggling Quagmire cause you to use 9 MP from your personal mana reserves. (2022-04-02 14:01:28).
- Your pet, Cosimo (a Ghoul), has been rejuvenated. You spent 10 Magic Points. (2022-04-02 14:01:31).
- Kwazirr drew 1 Magic Points from Juggling Quagmire. (2022-04-02 14:01:31).

I rejuv a ghoul for 10 MP cost -- font goes down by 1 MP, I remain at 6 MP.