Using ${var} in strings is deprecated, use {$var} instead

Problem/Motivation

As of PHP 8.2 the use of `${var}` has been deprecated. This is returning multiple notices throughout the Opigno suite of modules. Working on replacing them.

Proposed resolution

  $key = implode('_', [
    $group_id,
    $uid,
  ]);

Will generate the same key string.

Related

Also to note, drupal_static will be deprecated in Drupal 11, so this will need to be addressed.

@see https://wiki.php.net/rfc/deprecate_dollar_brace_string_interpolation