I had a look at some of these logs, and all cases appear to be tripping
over the following change mentioned in texinfo's NEWS file.
,----
| 7.0 (7 November 2022)
| * texi2any
| . HTML output:
| . use manual_name_html as output directory for split HTML instead of
| manual_name or manual_name.html
`----
Which seems to rather gratuitously break existing Makefiles left and
right. Actually it surprises me that only 15 packages FTBFS due to that
incompatible change, there will likely be other cases where HTML
documentation silently goes missing. :-(