Crawling broken on D11

Problem/Motivation

Maybe the main error:
Deprecated function: Creation of dynamic property Drupal\boost\BoostCacheGenerate::$config is deprecated in Drupal\Core\Batch\BatchStorage->load() (line 57 of core/lib/Drupal/Core/Batch/BatchStorage.php).

Maybe just a follow up error:

Warning: unserialize(): Error at offset 13300 of 49995 bytes in Drupal\Core\Batch\BatchStorage->load() (line 57 of core/lib/Drupal/Core/Batch/BatchStorage.php).

Steps to reproduce

Using composer test with lenient on D11 and try to crawl.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes