Breaks on WordPress 6.9

I have a similar “Map breaking into tiles” error like others, and only solution was to rolling back to WP 6.8.3.

Probably that is why: (ChatGPT answer)

WordPress 6.9 introduced some changes in how shortcodes and do_shortcode() handle attributes, especially URLs with query strings.

• Your ?api_key=… in tile URLs may have been partially mangled or treated differently in JS initialization.
• This caused some tiles to fail or “undefined” requests to appear.

1., I use a custom build website, no page builder used with shortcode in PHP file

2., Leaflet Map (Version 3.4.2) and Extensions for Leaflet Map (Version 4.9)

3. I got a lots of error: “GET /tiles/stamen_watercolor/8/121/94.jpg?api_key=… undefined” .The undefined comes from Leaflet or the plugin: it’s trying to append something to the URL, but the variable is undefined.