(Remote) debugging in conjunction with QProcess not possible (gdbserver: PID mismatch!)

I have code which must run with root privileges. To be able to debug it with QtCreator I have created a "Kit" with a "Generic Linux Device" in QtCreator, which connects to the localhost with a SSH key as user root.
My code starts external processes via QProcess. When calling the function start() on my QProcess member variable the debugger ends with the following error message:

gdbserver: PID mismatch! Expected 1292, got 1286
gdbserver: Cannot find thread after clone.

Child exited with status 0

The code in the attachment is sufficient to trigger the problem.
With Qt 5.15.0 it is working fine, since 5.15.1 the debugger crashs.

I have previously reported the bug to the distribution: https://bugs.archlinux.org/task/67904