Table block – Wrap table

You can search for the <table> strings and replace them with the wrapper element:

function pb_table_render_block($block_content, $block) {
    if ($block['blockName'] == 'core/table') {
        $block_content = str_replace('<table', '<div class="table-wrapper"><table', $block_content);
        $block_content = str_replace('</table>', '</table></div>', $block_content);
    }

    return $block_content;
}
add_filter('render_block', 'pb_table_render_block', 10, 2);