Polylang + ACF: Better Search timeout on pll_posts_not_translated

Posting this here for future reference.

ACF: Better Search’s modifications to any WordPress search query can significantly slow down Polylang’s pll_posts_not_translated AJaX request, which may lead to timeouts when using the autocomplete box to link translations in the Polylang language metabox.

ACF: Better Search (ACF:BS) can be disabled through code using the acfbs_is_available filter.
Following this, ACF:BS can be disabled specifically for the Polylang translation linking feature using the following code.

if ( wp_doing_ajax() && isset( $_GET['action'] ) && 'pll_posts_not_translated' === $_GET['action'] ) {
  add_filter('acfbs_is_available', '__return_false');
}

This code can be placed in your theme in functions.php.