When scanning a custom module, render arrays with #lazy_builder are flagged as incompatible when the lazy builder is not a callable. However, the #lazy_builder syntax accepts noncallables in the form of service.key:methodName. See \Drupal\comment\Plugin\Field\FieldFormatter\CommentDefaultFormatter::viewElements for an example of this pattern in core.
Run against a module which uses the service key pattern instead of the callable pattern.
Support the service key pattern, or flag uses of #lazy_builder which do not have a callable as a warning rather than an error.
Create patch.
None.
None.
None.
Postponed
4.0
Code
The fix would be in phpstan-drupal, this is where its checked: https://github.com/mglaman/phpstan-drupal/blob/a19934c9523f301883a4eedaf...
This is related: https://github.com/mglaman/phpstan-drupal/issues/561
Postponing because there is nothing we do within Upgrade Status and the underlying phpstan-drupal logic should be fixed.