Exam PCCSE topic 1 question 22 discussion

An S3 bucket within AWS has generated an alert by violating the Prisma Cloud Default policy `AWS S3 buckets are accessible to public`. The policy definition follows: config where cloud.type = 'aws' AND api.name='aws-s3api-get-bucket-acl' AND json.rule="((((acl.grants[?(@.grantee=='AllUsers')] size > 0) or policyStatus.isPublic is true) and publicAccessBlockConfiguration does not exist) or ((acl.grants[?(@.grantee=='AllUsers')] size > 0) and publicAccessBlockConfiguration.ignorePublicAcis is false) or (policyStatus.isPublic is true and publicAccessBlockConfiguration.restrictPublicBuckets is false)) and websiteConfiguration does not exist"
Why did this alert get generated?