I get this message when I choose: Dropdown or Modal

I get this message when I choose: Dropdown or Modal
when I set up shipmondo in woocommerce

Deprecated: implode(): Passing glue string after array is deprecated. Swap the parameters in /customers/3/b/2/oldestrik.dk/httpd.www/wp-content/plugins/pakkelabels-for-woocommerce/lib/tools/trait.templating.php on line 40

When I’m on the page where customers have to pay, this message is also at the top of the page.

I’ve tried everything soon, but can’t figure out what’s wrong. Is there anyone who can help me with this ??
Thanks in advance

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