Is redacting PII with Adobe or similar tools actually safe, or can it be reversed?

A member's son, who works in AI, raised concerns about data safety: if you use a public LLM, your data may be used as training data, and there are known ways to 'bully' an AI into revealing training data even when it's not supposed to share it. On document redaction specifically, using a local script to strip PII is probably fine as long as it truly redacts the data. However, the group noted that some people using Adobe to redact PDFs found the redacted information could be easily added back in, apparently because it was still saved in the metadata. The takeaway is that redaction tools must be checked to ensure removed information isn't recoverable from the file's metadata.