Strange reports about my apple id

In the past few days I have had a total of 3 notifications on my iPad that my apple id has been used

1) a message that the apple id has been used somewhere in a place where I am not present due to holiday abroad

2) my apple id was used to login to i message (no idea what this is but that aside)

3) my apple id was used to log in to a new iphone

all messages appeared in a flash and i couldn't save

no one knows my apple id

I once set up a two-factor authorization, this was not requested

I changed my password just to be safe

my question is how can i get these notifications without me not being the one who did these activities?

I have checked whether purchases have been made from my apple id but that is not the case

find it very strange