Heading levels that jump - WCAG 1.3.1
skimming is navigation; here's how it breaks
Screen reader users navigate by pulling up a list of headings, the way a sighted reader's eye skims a page. When a document goes from h1 straight to h4, that list implies two levels of structure that do not exist, and the reader loses the shape of the chapter.
The hand-fix
Renumber so no heading is more than one level below its predecessor: h1, then h2, then h3. Do not choose heading levels for their size; that is what CSS is for.
What Reflow does
Heading repair is a proposal, not an automatic fix. It arrives in job setup unticked, because renumbering changes the structure a person authored. Approve it and the repair is deterministic (h1 then h4 becomes h1 then h2, cascades handled, attributes preserved) and every closed jump is logged individually on the audit trail with the heading text before and after.