Dear Maintainer, tried to reproduce this issue inside a minimal qemu VM and found that this starts to manifest with kernel version 5.9. Using a kernel 5.8 with current testing userland does not show this issue.
These tests were done with qemu parameter "-cpu host". Without any cpu parameter I could not detect this fault in this VM. Unfortunately I read the linked issue too late were investigation continued already (and points to a gdb upstream patch), so this seems to be a feature, added to the kernel, uncovering this bug in gdbserver. Building a gdb package, with this upstream patch included, does not show this issue. Kind regards, Bernhard