This does bring up the value, especially in larger accounts, of using a service account. This would be a license dedicated to creating automations and integrations - that can persist through staff changes (just change the password!). Not a free solution, but if you have hundreds of users, hundreds of boards with complex workflow - this is the best bet to avoid disruptions in service.
The best solution is what @codyfrisch described here, have a dedicated account for automations and integrations. In the October update a new feature is mentioned to transfer ownership of integrations when deleting a user. Brand new - I did not test it yet - but it looks promissing.
Correct - custom recipes that use integration blocks as actions or triggers will need to be recreated from scratch.
All more reasons to maintain a service account if you’ve built complex workflows. (and make sure the other admins on the account know you created it and how to handle it… so if you abruptly leave they don’t deactivate and then fully delete the account immediately. Yeah seen that happen.)