Linux Platform for Dockerfile
I had no idea that docker uses the underlying platform as default also for images that it installs. My Dockerfile that just contained FROM ubuntu and I ran some linux binary in there, it threw:
qemu-x86_64: Could not open '/lib64/ld-linux-x86-64.so.2
Fortunately there is stackoverflow https://stackoverflow.com/a/71611002
Changing my Dockerfile to start with the following, fixes it:
FROM --platform=linux/amd64 ubuntu
Interesting.