https://bugs.winehq.org/show_bug.cgi?id=53032
--- Comment #23 from Bernhard Übelacker bernhardu@mailbox.org --- glibc checks for the thread being the last thread and then executes the exit() call I see in the backtrace.
Maybe some race condition, which thread is the last one?
https://sourceware.org/git/?p=glibc.git;a=blob;f=nptl/pthread_create.c;h=6c6... (This is 2.33, similar to Debians version. There were some changes to start_thread between 2.33 and 2.34 which is used in Fedora.)