Select Portfolio Servicing review: Payment amount variation.

My mortgage payment varies every now and then. My monthly payment was $422.00 and now has gone up to $644.00. I am on a fixed interest rate of 4.25. My loan was modified in 2010 and sold by Chase Bank to SPS around 2018/19. I don't know, but it seems way too shady. 35% increase on my payment all of a sudden? Is that normal, and what can I do. Anybody who can explain that to me?