Your "Bonus" was much higher in January.
Employers sometimes have an option for this, but usually non-bonus income is based on your W-4, but Bonus income is withheld at a flat 25%.
However, that still would be too much withheld. Because it is EXACTLY 25%, it seems like ALL of your income is being withheld at the flat 25% for Bonuses. It is likely a mistake (either whoever does payroll or the software that does payroll). You may want to speak to HR about it.
