That is strange. The go team doesn't introduce breaking changes in point releases. Here are the changes for go1.21.5, none of which look particularly relevant.
The code is crashing in
runtime·asmstdcall which is an assembler routine and the way Go calls the Windows runtime.
I don't propose to investigate this further since the Go team have already said go1.21 will require Windows 10 or later so I think filing an issue wouldn't be productive.
Maybe rclone v1.65.0 was working accidentally somehow?
Note that you can compile v1.65.x with go1.21, go1.20 and go1.19
You'll be able to compile v1.66 with go1.22, go1.21 and go1.20
So you'll be able to have the latest rclone for a bit longer on Win 7 if you are willing to compile it yourself.
We probably should be talking about this somewhere...
And yes we should probably state v1.63.1 as being the last version as I don't know why the later ones are working at all, and maybe they will blow up in some different way.
We should probably have a little section in each architecture in the install doc, eg here is the windows install
This could have a little table something like this (probably not correct)
|Supported Windows Versions
|Windows 10 or later, Server 2016 or later
|Windows 7 or later, Server 2008 or later
We could have a similar table for macOS versions and for linux kernel versions.
To make these tables this will need a bit of software archeology looking up the go release notes and working out which rclone was compiled with which go version.
The download page should probably show a summary table something like this for the latest versions
Required OS versions
I got those figures from the go download page which are for go 1.21
@kapitainsky can you make an issue about this and we can start collecting the data for the various doc sections - thank you