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 Jira is
Jira wiki markup uses double pipes for header cells and single pipes for data cells.
Jira issues, comments and descriptions.
What changes when you convert YAML to Jira
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.
Empty cells are filled with a single space, because a Jira row with two adjacent pipes collapses the column and shifts everything after it.
What carries over from YAML to Jira
YAML records 4 things about a table that Jira has no way to hold.
YAML distinguishes a number from the text of a number; Jira does not, so every value arrives as text and has to be re-parsed by whatever reads it next.
An empty cell and a missing one are the same thing in Jira, 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. Jira has only flat cells, so nested values are flattened into one cell rather than being spread across columns.
A line break inside a cell ends the row in Jira, so line breaks are replaced rather than carried through.
Jira marks header cells differently from data cells, so the keys are lifted out and written once as a marked header row rather than repeated on every row.
The identifier 007 comes out of the Jira as 007. Reading it as a number would have made it 7, and an id that changes value is worse than one that stays text.
The role "Analyst, data" survives with its comma, in one cell rather than split across two. That is the first thing to check in any converted table, and the usual place a Jira file goes wrong.
The quotes around Jonah "Jo" Pryce are left as a plain quote character in the Jira.