Restrict Allowed Block Types for Posts

add_filter( 'allowed_block_types_all', 'wpfolks_allowed_post_blocks', 10, 2 );

function wpfolks_allowed_post_blocks( $allowed_blocks, $editor_context ) {
    if ( empty( $editor_context->post ) || 'post' !== $editor_context->post->post_type ) {
        return $allowed_blocks;
    }

    return array( 'core/paragraph', 'core/heading', 'core/image', 'core/list', 'core/quote' );
}