https://bugs.winehq.org/show_bug.cgi?id=50440
--- Comment #27 from Giuliano pochini@shiny.it --- Well, this is not the same problem as mine. Wine did not complain about missing libraries or anything. I compiled 6.19 and 7.x on the same system with exactly the same config. One worked and the others did not. That's why I thought it was wine's fault. Recompiling the same version of gstreamer fixed it (I had to install temporarily an older version for a test). So I'm baffled and I don't know what was wrong, but at least now we know that gstreamer has an important role.
For anyone who is having similar problems: I suggest to check if gstreamer and its plugins are installed in both amd64 and x86 (32 bits) versions.