I tried to override phtml template for order_info block in Magento order shipment view layout like this:
app/code/Namespace/Module/view/adminhtml/layout/adminhtml_order_shipment_view.xml
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="order_info">
<action method="setTemplate">
<argument name="template" xsi:type="string">Namespace_Module::order/view/info.phtml</argument>
</action>
</referenceBlock>
</body>
</page>
app/code/Namespace/Module/view/adminhtml/templates/order/view/info.phtml
<h1> Success </h1>
after i cleared cache and setup:upgrade, nothing changed, it still loads the magento core phtml