Hello! Sorry for necroposting, but Google finds no similar thread elsewhere. I seem to have the same problem with HDMI audio output (to a TV) - during about 1 sec half speeded-up/half silence. What I noticed, is that when I set audio to direct output (my TV has support for AC3 only, so I used a file with AC3 audio track), the speeded-up part became normal, but the part with silence remained.
A workaroud that I found (KIND OF) was to set the UI refresh rate to 25Hz, and the sound came back to normal. My file was a 1080i 50fps one, so the video was lagged/distorted occasionally. Probably I had to switch off the correction of display rate to match the file, too.
A bad thing is that I don't have a way to reproduce it. It seem to not depend on rebooting and any of the previous settings and files played. Some time after (maybe just next day), it becomes normal again. My set up is a LibreELEC 11.0.6 x86_64 VM with a AMD Radeon video card passed through (both VGA and audio PCI functions) connected to an LG TV. The host (Debian 12 on Linux 6.12) has two such video cards (on PEX 8747 PCI switch), attached to different VMs, and a strange coincidence (not sure) is that when this audio thing happens to LibreELEC, I try to reboot, and only one the cards appear on the host, and again, the next day I reboot to normal. So I begin to suspect moon phases (or just timers divided by some epoch days). Hope this helps someone to debug this problem further.