PNG can capture build time with the tIME chunk or custom keywords. These timestamps are currently removed by strip-nondeterminism, so are not visible to diffoscope anymore. Yet fixing the root cause would be nice.
eg. %%CreationDate (or DVIPSSource?) in header . https://sources.debian.net/src/texlive-bin/latest/texk/web2c/pdftexdir/pdftex.web/#L14449 . DVIPSSource date Can be set to SOURCE_DATE_EPOCH by setting FORCE_SOURCE_DATE to 1.
The creation date of the DVI file is the current time.
Our notes about issues affecting packages are stored in notes.git and are targeted at packages in Debian in 'unstable/amd64' (unless they say otherwise).