The various test-suite.log files show different test failures each Yes. Painful. I believe this is due to a timing problem with autom4te, exposed by Automake using fractional second sleeps according to what the filesystem supports. It is fixed in the autoconf repository but hasn't been released.
I also noted this and asked for help earlier this year. Bogdan and many other contributors looked into it, and Bogdan eventually came up with a (tiny) patch for autom4te, which Jacob forwarded to autoconf here: https://lists.gnu.org/archive/html/automake/2023-03/msg00039.html and it got installed. I don't know if there is an associated autoconf bug#, but probably? For myself, I can report that when I made the change (< to <= in two places) in my live autom4te, it did not completely fix the timing failures. I don't know why not. I bootstrapped and installed autoconf from its git (as of around June 11) and have used that version with development automake ever since, and the timing problems have stayed gone. (This fix is what has allowed me to get back to doing any Automake maintenance at all, so thanks again, Bogdan & everyone!) Jacob developed a change to allow automake to test whether the autom4te fix is in place or not, to avoid requiring the latest autoconf, but I haven't installed it yet -- see thread continuation starting at https://lists.gnu.org/archive/html/automake/2023-04/msg00002.html. (If anyone has time to turn the code into the full expected patch, that would be great.) Thanks, Karl