What YAML is
YAML uses indentation instead of brackets. It is a superset of JSON, supports comments, and is meant to be edited by hand.
Kubernetes manifests, CI pipelines, Ansible playbooks and most modern config files.
What PDF is
PDF describes a page: glyphs at coordinates, not rows and columns. A table in a PDF is a visual arrangement, not a data structure.
Reports, invoices, statements and anything sent to be read rather than processed.
What changes when you convert YAML to PDF
A YAML list of maps reads as rows and columns directly. Anchors and aliases are resolved before the table is built, so a repeated block arrives expanded rather than as a reference.
The table is drawn into a paginated document with the header repeated on every page, so a long table stays readable past page one. Page size, orientation and font size are all adjustable.
What carries over from YAML to PDF
YAML records 4 things about a table that PDF has no way to hold.
YAML knows which of its values are numbers. PDF keeps only their appearance, so nothing downstream can sort or sum them without someone reading them back off the page first.
An empty cell and a missing one are the same thing in PDF, so a null and an empty string in the YAML both come out blank and can no longer be told apart.
YAML can hold a value that is itself a list or an object. PDF has only flat cells, so nested values are flattened into one cell rather than being spread across columns.
PDF is the end of the line for this data. Reading the table back out of it is a separate and much harder problem than writing it, so keep the YAML if you will need the values again.