Symfony version(s) affected: 4.4

Description
When form with object $data type ArrayAccess (example Doctrine ArrayCollection) is validate and the field use 'property_path' => '[key]', is generated wrong validation path -> [[key]].

How to reproduce
Create a form with data type ArrayCollection and add field with property_path => '[key]'. Then insert wrong value and validate.

Here a piece of wrong code (in my opinion)