It's unusual, but ordinarily has no effect: your monthly salary is fixed at 10000, and you get that regular amount each month, and pay the same amount of deductions (tax, insurance, pension...) each month.
It may well have a bearing on overtime payments. Four hours' overtime in January would be 0.5 × 476 on your calculation in the question. In February 2021, there are 20 working days which works out at 500 per day and four hours' overtime is 0.5 × 500. In March, there are 23 working days and the daily rate is lower than January. (So, actually, February is the month which definitely doesn't have a downside here!)
It almost certainly will have an effect for unpaid leave. An unpaid day in January will cost you 476; an unpaid day in February will cost 500. A day in March is worth 434. February does have a downside here.
The employers I've worked for have set an annual salary which is simply divided by 12 for monthly payments or 13 for four-weekly payments. The annual rate is then divided by a notional number of working days in a year (365 − 104 = 261) to get a daily rate, and the hourly rate which is used for overtime is 5 × (daily-rate) ÷ (weekly hours). Because the notional number of working days is close to the actual number, the calculated daily rate is reasonable, and it doesn't vary through the year. It makes calculations easy for everyone.