MongoDB Atlas No of connections

has anyone noticed higher numbers of connections than usual in Atlas? The first shot is from a project with 0 users (0 sessions). It might be that the connection pool size behavior has changed with the newer mongo drivers. A second shot is the growth over a year. I see a constant increase in the number of connections while this project was under development with 1-2 concurrent users. The servers have been restarted many times in these months and presently after a restart on the Primary the number of connections goes down to ~20 users just to start increasing again up to 50.