3 year old accidents

My now 3 year old has been potty trained since 16 months old. Full potty trained, through the day and night. For the past month she has been peeing almost every night or whenever she takes a nap in her clothes. Has anyone experienced this with their little one? What did you find useful? She does have a younger sibling that has just entered the potty training stage and she has been wanting all the cool pull ups, but idk if that plays a factor in her accidents.