incorrect calculation of experience

We defeated a strong opponent, after which we were given 2,520 experience points. level 4 was set in the character's card, but it is written in the game that the level is set to 2. there was also a wrong calculation of hp. the next time we gained experience, we noticed that there were discrepancies in the maximum experience before moving to the next level (also at the beginning of the company, we set the character's level to 2, but it later reset to 1)