Bug archives page

Hello,
I am updating a client’s site. Locally, I’m having a problem with the archive page. The content is present on the page but an error is displayed: Warning: Uninitialized string offset 8 in /Applications/MAMP/htdocs/wordpress-test/wp-includes/functions.php on line 294
The error therefore comes from the functions.php file of wordpress, my theme is not a problem.
I can’t find any solutions.
The version of events manager is 5.12.1 and the version of wordpress is 5.9.2.
Archives are displayed via the following shortcode:
[events_list scope=”cal-event” scope=”past” orderby=”event_start_date” order=”DESC”]
Can you help me ?
Thank you!`