Zynthian not booting because of `cmdline.txt` broken by update

Now it has happened for the second time, always after an update (since I switched to the Vangelis branch, I think): Zynthian suddenly cannot boot. A look at the SD card shows cmdline.txt was overwritten with some binary contents (maybe even the exact length of the original contents?). Any idea what’s going on here? Am I the only one with this strange issue?

(So glad I bought the SD card extension and don’t have to disassemble the whole embedded thing every time now!)

Could be the extension making problems.
With Pi 5, signals are now so fast, they will not pass an ordinary extension without becoming distorted or out of timings.
Then there could be the card itself being the problem.
So, better use no extension, use a good microSD, and problems will likely disappear.

I’ve set the boot order to USB first, wich gives me the option to boot a Raspberry Pi OS as sort of a “rescue system” and dd images and backups, or at least check partitions and restore broken settings.
The little penalty time at boot gives a lot more options than swapping cards, or worse, NVMe.

I have been considering those possibilities too. I have already had the SD card replaced, because it died shortly after I bought it. It is a “Kingston Canvas Go! Plus” (A2-class) card. But why does it concern only one particular file…?

The extension seems to be of good quality - ADTlink B11SF. But nowadays, one cannot rely on anything, of course. Without it the card is basically inaccessible unless I use a lot of effort, disassemble lot of things… But the possibility to use a rescue flashdisk via USB seems quite a plausible solution in case things show broken, thanks.