It seems that setting the component values of a vector via a Set node in Control Rig can effect the default values of other blueprint variables in the Control Rig. See the attached video for more details. Note that this only happens when you set the components pins of a vector, not when you set the vector pin directly. This also repros in UE5-Main.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-115468 in the post.