@modulux I'm a bit worried because Pinafore and Semaphore are unmaintained. You cannot even open an issue to Semaphore. I'm using Enafore, which is mildly active.
You could try what happens with Enafore.
Otherwise, I think all three are based around an outdated version of Svelte... you could open a Firefox bug? But I wouldn't put a lot of hopes there :(