Power stroke : unwanted thickness changes when editing bsplines

Steps to reproduce:

• With pen/bezier tool (Maj+F6), bspline mode with no shape, draw a simple curved path . Apply power stoke LPE
• optional : with node tool (F2) set desired width.
• with node tool (F2) add a node on path (double click on red line between two nodes): stroke thickness changes a lot (thicker). With a regular bezier path or spiro one no.

What happened?

Thickness stoke settings changes when a node is added.

What should have happened?

Width stoke should not change. With a regular bezier path or spiro one no thickness changes occur.

Related bug

Undo step after the described steps leads to an "Undo bug" : see issue 1446.

Inkscape Version and Operating System:

Inkscape 0.92.4 and 1.0beta2 (418fe52, 2019-12-12) on windows 8.1

Thank you for listening !