Tenebra freezes the core (RetroArch gets pegged at 100% CPU)

In Tenebra, when entering the exit gate of a level from above, the core becomes unresponsive (even RetroArch hotkeys stop working). Looking at the list of processes, I can see retroarch pegging the CPU at 100%.

If I leave it there for a while, it eventually unfreezes after a few minutes and the game continues. If I switch from the default "Spectrum 128K" to "Spectrum 48K" in the core options, it still freezes, but takes much less time (under 10 seconds) to recover.

I'm running a RetroPie-based setup (RetroArch 1.19.1) on Ubuntu 22.04 (x86-64), with lr-fuse compiled from source at commit cad85b7b1b864c65734f71aa4a510b6f6536881c.

I've tested with other emulators (JSSpeccy 3, QAOP), and also with "The Spectrum" and it doesn't happen in any of those.

Steps to Reproduce:

1. Load tenebra.tap;
2. Press space until entering the first level;
3. Approach the exit gate from above;
4. Move down to enter the gate;
5. The game freezes instead of moving along to the next level.

Reproduce the freeze with tenebra.tap in lr-fuse, following the listed gate-entry steps, and compare the Spectrum 128K and 48K core options. Start by tracing the core's handling of the level transition; done means entering the exit gate advances without pegging RetroArch's CPU or disabling its hotkeys.