Hello ElsaAnne!
We see you are having some trouble with your iPhone 11 taking random screenshots from time to time. That is definitely unexpected, we'd like to help! Do you have a case on that device by chance? Try removing the case and seeing if the issue continues to see if it is related to the case pressing the buttons on the device. We have a few other questions to help narrow this down as well. Did this issue start after anything specific such as an update or changing any settings? Have you noticed it occurs at any specific time for example when using certain apps or only when the display is locked?
Have a great rest of your day!