Steps to reproduce the issue

1. Create a Content Field of type List with Multiple Values (Multiple option as Yes) called "myfields" (for example).
2. Enter two or more values in "List Values"
3. Create an Article and in the Fields Tab, select multiple fields and save
4. Call with the API to the created ID article {{base_url}}/{{base_path}}/content/articles/your article id

Expected result

A json list with data

Actual result

"errors": {
"code": 500,
"title": "Internal server error",
"detail": "TypeError: Illegal offset type in

System information (as much as possible)

Php 8.0
Joomla J4.2

Additional comments

The problem is in onCustomFieldsBeforePrepareField from list.php.
in the line $field->apivalue = [$field->value => $options[$field->value]];
if $field->value is multiple (an array), it returns error.