403 forbidden error when job tries to push image

After migrating our gitlab architecture onto the Gitlab-environment-toolkit, the following error occurs when trying to push an image run a job via gitlab project ui.

error pushing image: failed to push to destination registry.xxxxx.xxxx.com/firstname.lastname/test2024oct:9af2a961: PATCH https://registry.xxxxx.xxxx.com/v2/firstname.lastname/test2024oct/blobs/uploads/e1fd9fa5-86af-43f6-b910-08566befa0b3?_state=REDACTED: unexpected status code 403 Forbidden: <html>
<head><title>403 Forbidden</title></head>
<body>
<center><h1>403 Forbidden</h1></center>
</body>
</html>

Does anyone know what could be the cause? I've tested a number of different configurations without success.

Edited Oct 06, 2025 by 🤖 GitLab Bot 🤖