If you accept the bonuses right away, you are required to repay a majority of the money if you resign prior to 2 years employment.

from Mirriam Webster: Definition of bonus
: something in addition to what is expected or strictly due: such as
a : money or an equivalent given in addition to an employee's usual compensation

So... it's not a bonus. It's an advance on future pay. Or... maybe they are under paying you up front?