2.5 y/o taking diaper off at night. Any advice?

For the past couple of days, my 2.5-year-old has been taking her diaper off at night. (It's not particularly full when she takes it off; she just doesn't seem to like having it on.) This morning she pooped without her diaper on and we woke up to a mess.

Has anyone else dealt with this? Any advice would be appreciated!