Dear Maintainer,
Thanks for this VERY useful program.
A syntactically correct (amsmath for flaalign)
\begin{flalign} \log{{ ...something... }} \end{leftalign}
causes an unwanted MATHBLOCKflalign in the diff file (I'm using latexdiff-vc with git).
The use of {{ instead of { is a leftover of a wrapping deleted command.
I attach:
zm4-oldtmp.tex = a fixed version of the offending command (HEAD^)
zm4.tex = as the previous one + a new equation with the offending command (HEAD),
zm4diffHEAD^-HEAD.tex = output of latexdiff-vc --git --ps -r HEAD^ -r HEAD --force zm4.tex
regards
ric