magento2: [Magento 2.4.4] Class magento/zendframework1/library/Zend/Pdf/NameTree.php not compatible with PHP 8.1

Preconditions (*)

1. Magento 2.4.4
2. PHP 8.1

Steps to reproduce (*)

1. Go to the Sales Shipments page in admin. Select shipments and the “Print Shipping Labels” action.

Expected result (*)

1. Get a PDF with all the shipment labels

Actual result (*)

1. PHP crashes with the following error :

Fatal error: During inheritance of ArrayAccess: Uncaught Exception: Deprecated Functionality: Return type of Zend_Pdf_NameTree::offsetExists($offset) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in vendor/magento/zendframework1/library/Zend/Pdf/NameTree.php on line 117

The error happens with the Magento\Shipping\Model\Shipping\LabelGenerator::combineLabelsPdf method.

Additional Information: Please refer below comment:

https://github.com/magento/magento2/issues/35335#issuecomment-1103902652

---

Please provide Severity assessment for the Issue as Reporter. This information will help during Confirmation and Issue triage processes.

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• [*] Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.