my almost 4 year old and 20 month old aren’t sleeping anymore 😳 is it a sleep regression?

so my kids have both always been really good sleepers. my almost 4 year old (next week) for this past week has been going to bed reallllly late. he typically goes to bed at 7 and he’s exhausted and goes straight to bed. lately he hasn’t been falling asleep until 9:30pm sometimes even 10pm. but he still wakes up at his typically time - 7am. then he’s cranky during the day.

my daughter who is 20 months, hasn’t been napping the past few days or possibly the week (i can’t exactly remember). as a result, she’s cranky as well.

im almost 20 weeks pregnant and exhausted. i really need them to get back to their normal schedules. any ideas why? is there a sleep regression at 20 months? is there a sleep regression at 4 years old? ugh!!!