PHP Error

Hello!
I get an error message as soon as I try to add the map.

Warning: Use of undefined constant veranstaltung_ort – assumed ‘veranstaltung_ort’ (this will throw an Error in a future version of PHP) in …

I am on PHP 7.4.1, WP 5.6.1 and MYSQL 8.0.16

Any ideas how this can be solved?

The map is still shown, but accompanied with this error message