[NTG-context] underbraces get progressively more misaligned (w/ minimal example)

It does also depend on the width of the text because when I use 48pt in the example below the height of the brace is always the same but with 49pt the height increases after the first page.

An experiment: width = 48.0719985pt height = 4.968pt (constant) width = 48.0719986pt height = unpredictable various values Best regards, Akira