1.2.4 Captions (Live) is a Level AA criterion that requires captions for all live audio content in synchronized media.
Testing Methods: Live Captions

1.2.4 Captions (Live) is a Level AA criterion that requires captions for all live audio content in synchronized media.
WCAG 1.2.2 Captions (Prerecorded) is a Level A Success Criterion requiring captions for prerecorded synchronized media, unless it’s clearly labeled as a text alternative.
WCAG 1.2.1 (Audio-only and Video-only – Prerecorded) is a Level A requirement. It mandates alternatives for prerecorded audio-only (e.g., transcripts) and video-only content (e.g., audio descriptions or text alternatives).
People in their early stages of their accessibility journey are often confused about the Web Content Accessibility Guidelines (WCAG) Conformance levels and what the expectations are to meet them. Here’s a quick glimpse into their meaning and how you should approach them.
There’s a lot of chatter on the intertubes of late around the thoroughness and accuracy of various accessibility testing approaches; Manual, Automated and AI-based testing. I thought it might be good to take a look at these comparisons, to have a better sense when different approaches can be effective.