Mysterious atime changes

I have a customer running a November update to 13.0 formerly 11.2 .

ZFS mirror with no exotic features used, normal Samba 4.13 port, common 
MS Windows clients. Perfectly common share definition configuration.

A problem came up with Solidworks whinging about clocks. Like so many 
error messages the real problem was something else specifically atimes 
of files getting set to Jan 19 03:14:07 2038 and this happens in front 
of my eyes on open files. The affected files are not just Solidworks but 
also Excel (unless they're using something else to write .xlsx files 
which I doubt).

So what could be going on (bearing in mind this happened with 11.2 as 
well) ? There's something at the client end (at least Solidworks and 
Excel), Samba, FreeBSD, old ZFS and OpenZFS involved.

Also 2038 isn't exactly what you expect with 64 bit systems and not that 
far in the future.

For fun I scanned my own server which is a syncthing dump and found only 
some Zwift files which syncthing had brought over from my Mac sometime 
mid-pandemic. On my Mac they don't have future atimes but just maybe 
they did when syncthing picked them up. Or is this the same filesystem bug ?

If anybody wouldn't find a quick look on their own machines I'd be 
interested to know. They're easy to find like this.

find somewhere -atime -0 etc.

Jon