when using the branch filter on the activity tab the design "jumps" to the right.

If you go to https://ci.blueocean.io/blue/organizations/jenkins/blueocean/activity and then click on the branch filter and use a branch with few builds like e.g. "neo-ath" you will see "movement" of the whole design shifting to the right, when the vertical scroll bar disappears.

See the video at https://youtu.be/Z8qx5fdZhvQ