Federal tax refund very low

I noticed that my federal refund is very low. I used to get around 950 for my refund but now it’s 137. Looks like state tax is correct. Also I never changed anything on my w4 from paychecks it’s always been the same since I started so I know it couldn’t have been that. I also noticed federal tax is very low on my paychecks. Around 250 for the whole year instead of the normal 900ish. Any idea what’s going on? Also I live in Connecticut if that helps.