the bug is still present in linux-image-6.10.3-rt-amd64. this bug appeared in linux-image-6.9.12-rt-amd64, downgrading to linux-image-6.9.10-rt-amd6 fixes this bug.
i compiled the linux kernel directly from kernel.org and it seems it's not a debian issue. i will perform a git bisect to pinpoint which commit is buggy tomorrow.
