I think they changed compiler and in the process changed from one MS runtime (MSVCRT) to a new one MS runtime (UCRT)

Yes - Winlibs are still providing both flavours.
I initially thought I had a UCRT build of perl-5.38.0, and a second MSVCRT build of perl-5.38.0 - both of which were exhibiting the same behaviour.
But it turns out they were both MSVCRT. (Silly me - UCRT mingw-w64 builds of perl weren't enabled until about 5.39.2.)

I agree that it will be the switch from MSVCRT to UCRT that has introduced the change. And this is further supported by the fact that my VS 2022 (UCRT) builds of perl show the same behaviour as my mingw-w64 (UCRT) builds.

Cheers,
Rob

In reply to Re^4: [Win32] Weird behavioural change between 5.38.0 and 5.40.0 by syphilis
in thread [Win32] Weird behavioural change between 5.38.0 and 5.40.0 by syphilis

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