Hierarchical List of Terms like breadcrumbs

No filter can be applied?

OK, I understand.

I’d like to share a solution that we have figured out with ChatGPT 😉
It works in regular GeneratePress theme / GP Premium (archives, search results, single posts), not in GenerateBlocks.

/**
 * Filter post categories output to display hierarchy (Parent > Child),
 * removing standalone parents if they already appear in a child chain.
 * Wrap each chain in <span class="chain">…</span>.
 */
add_filter( 'the_category', function( $thelist, $separator = ', ', $parents = '' ) {
    global $post;

    // Do nothing in backend
    if ( is_admin() ) {
        return $thelist;
    }

    if ( ! $post ) {
        return $thelist;
    }

    $categories = get_the_category( $post->ID );

    if ( empty( $categories ) || is_wp_error( $categories ) ) {
        return $thelist;
    }

    // Collect all parent IDs used in any chain
    $parents_in_chains = [];

    // Build all category chains
    $chains = [];
    foreach ( $categories as $cat ) {
        $chain   = [];
        $current = $cat;

        while ( $current ) {
            $chain[] = $current;
            $current = $current->parent ? get_category( $current->parent ) : null;
        }

        $chain = array_reverse( $chain );
        $chains[] = $chain;

        // Save parent IDs (exclude the leaf itself)
        foreach ( array_slice( $chain, 0, -1 ) as $parent_term ) {
            $parents_in_chains[] = $parent_term->term_id;
        }
    }

    $output = [];

    foreach ( $chains as $chain ) {
        $leaf = end( $chain );

        // Skip standalone parents if they already appear in another chain
        if ( in_array( $leaf->term_id, $parents_in_chains, true ) ) {
            continue;
        }

        // Convert to linked names
        $names = array_map( function( $term ) {
            return sprintf(
                '<a href="%s" rel="category tag">%s</a>',
                esc_url( get_category_link( $term->term_id ) ),
                esc_html( $term->name )
            );
        }, $chain );

        // Wrap in span
        $output[] = '<span class="chain">' . implode( ' > ', $names ) . '</span>';
    }

    return implode( $separator, $output );
}, 10, 3 );