2.7 beta changes height for \| delimiter
2.7 beta noticeably shortens height for | delimiter without \left ot \right 2.6.1 seems to act more like what one would expect from TeX.
Screenshots are from https://cdi2tp.math.tecnico.ulisboa.pt/texto/14 See e.g. equation (1)
Version 2.6.1
Version 2.7 beta