Volatile Organic Compounds are indoor air pollutants [1]. For example, formaldehyde – classed as carcinogen – added to bind Medium Density Fibreboard (MDF).
This add-on shaped the privacy-positive landscape for browsers upon it's release, but the features have be made obsolete with the latest browser isolation and that most entities have migrated to bundled JavaScript and off of CDNs.
No E2EE for photos saved in iCloud, but they're encrypted in transit (SSL/TLS) and at rest (they get encrypted on the servers and not your device so not using E2EE).
You have to scroll a bit further down to see “End-to-end encrypted data” on the page you linked :)
[1]: https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-...