Income from 1099-INT is calculated at 40% rate. Instead of being taxed at 35%. I have compared W2 only, then added 10K from 1099-INT and it added up 4K more owed

Highest tax bracket is 37% and i'm well under, how 10K from 1099-INT adds up 4k to taxes owed? I expected to be at 35% rate and no other taxes as the amount above FICA taxable amount, etc..