Switching from Option 3 to Option 3x

Guys, i have a question.

When switch data split from LTE to gNB or from option 3 to 3x, is this action need alignment with the EPC Core as as mark in red?

S1-U need to setup when switch from 3 to 3x and need to be removed when switch from 3x to 3?

You can’t use option 3x and 3 simultaneously.

You need to choose one configuration.

Most used is 3x and data split is managed by the gNB using specific threshold.

Ok dear.

But I mean what is role of red mark connection here?

Should this interface between EPC and gNB setup when use 3x and removed when use 3 from Core side?