I'd bet that it's AI generated, resulting in the funky noise.
Oh, ding ding! Opening in a hex editor, there's the string "Added imperceptible SynthID watermark" in an iTXt chunk. SynthID is apparently a watermark Google attaches to its AI-generated content. This is almost certainly the noise.
alt Hacker News
Oh, ding ding! Opening in a hex editor, there's the string "Added imperceptible SynthID watermark" in an iTXt chunk. SynthID is apparently a watermark Google attaches to its AI-generated content. This is almost certainly the noise.