Is it safe to disable Temando_Shipping & Dotdigitalgroup_Email?

We can use the below command to make sure the particular module has any circular dependency.

php bin/magento info:dependencies:show-modules-circular

Above command generate one CSV file in magento-root-folder/modules-circular-dependencies.csv, please analyze this and make a decision.

Also, while disabling extension use the below command, it will throw an exception, if it has a circular dependency.

php bin/magento module:disable Vendor_Module

Yes, It's absolutely safe. However, you will lose the features provided by both the extensions.

Features:

https://temando.com/en/connectors/magento-2-shipping-software https://marketplace.magento.com/dotmailer-dotmailer-magento2-extension.html