I gave up. Even when I managed to get the ssd mounted, it randomly unmounted and was a pain to get re-mounted. I decided to connect the ssd to a linux machine and sync the data with rsync over ethernet. This has been running for hours now without issues. But I had to buy an usb-c to rj45 dongle. Actually, it was quite an adventure to find one 😆
Discussion
The problem is really interesting. linux systems are really much better but they don't get the attention they deserve
The funny thing is, these SSDs worked last year without problems. Also interesting, the SSDs are noticeably more stable on the Intel MBP than on the Silicon MBP. I think it’s related to the current macOS version.