Doctrine getRepository call cannot find class following composer update - php

Question

I have run a composer update on my Symfony 4.4 project and ran into an issue that will run throughout my project.
The following line:
$this->stadiumEntity = $this->getDoctrine()->getRepository('AppBundle:Stadium')
errors with:
Class AppBundle:Stadium does not exist
When I change it to the following it works, however there is clear some BC break in either Symfony itself or more likely one of the Doctrine packages. I just can't determine which one.
$this->stadiumEntity = $this->getDoctrine()->getRepository(Stadium::class)
I thought the issue was in doctrine/persistence, however the getRepository method hasn't really changed in 3 years.
composer show | grep doctrine
doctrine/annotations 1.13.2 Docblock Annotations Parser
doctrine/cache 2.2.0 PHP Doctrine Cache library is a popular cache implementation that supports many different drivers...
doctrine/collections 1.6.8 PHP Doctrine Collections library that adds additional functionality on top of PHP arrays.
doctrine/common 3.3.0 PHP Doctrine Common project is a library that provides additional functionality that other Doctri...
doctrine/data-fixtures 1.5.3 Data Fixtures for all Doctrine Object Managers
doctrine/dbal 2.13.9 Powerful PHP database abstraction layer (DBAL) with many features for database schema introspecti...
doctrine/deprecations v0.5.3 A small layer on top of trigger_error(E_USER_DEPRECATED) or PSR-3 logging with options to disable...
doctrine/doctrine-bundle 2.6.3 Symfony DoctrineBundle
doctrine/doctrine-fixtures-bundle 3.4.2 Symfony DoctrineFixturesBundle
doctrine/doctrine-migrations-bundle 3.0.3 Symfony DoctrineMigrationsBundle
doctrine/event-manager 1.1.1 The Doctrine Event Manager is a simple PHP event system that was built to be used with the variou...
doctrine/inflector 2.0.4 PHP Doctrine Inflector is a small library that can perform string manipulations with regard to up...
doctrine/instantiator 1.4.1 A small, lightweight utility to instantiate objects in PHP without invoking their constructors
doctrine/lexer 1.2.3 PHP Doctrine Lexer parser library that can be used in Top-Down, Recursive Descent Parsers.
doctrine/migrations 3.4.2 PHP Doctrine Migrations project offer additional functionality on top of the database abstraction...
doctrine/orm 2.12.2 Object-Relational-Mapper for PHP
doctrine/persistence 3.0.2 The Doctrine Persistence project is a set of shared interfaces and functionality that the differe...
doctrine/sql-formatter 1.1.2 a PHP SQL highlighting library