This is probably the most annoying default in PyYAML. It's the only PyYAML FAQ
entry: https://pyyaml.org/wiki/PyYAMLDocumentation#frequently-asked-questions

Changing the default to always prefer indented/block style would be good, but
is not back compatible. Since we will be breaking backwards compat big time
with the upcoming safe-load-by-default changes, this change should probably be
timed with that one.