wp-includes/class-wp-block-processor.php:1201Returns the depth of the open blocks where the processor is currently matched.
int public function get_depth(): int { return count( $this->open_blocks_at ); }Introduced in 6.9.0. Unchanged from 6.9.7 through 7.1.0.
Signature, return type and hooks compared across 3 parsed releases.
src/wp-includes/class-wp-block-processor.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.