Here are some good HDMI‑cables of ≈ 20 m length with 8K / 48 Gbps (HDMI 2.1

Highlights

• MX 8K HDMI 2.1 Fiber Optic Cable 20m — Solid all‑rounder AOC (Active Optical Cable) with full 48 Gbps, supporting 8K@60 Hz, 4K@120 Hz, HDR10, Dolby Vision, eARC and HDCP 2.3. Good if you want reliable high‑speed video over long distance.

• UGREEN HDMI 2.1 Male to Male Fiber Optic Cable 20m — A premium long‑range cable from a known brand. Fiber‑optic design helps maintain signal integrity over 20 m without interference. Excellent for home‑theater / gaming setups with PS5, 8K TVs etc. 

• Tobo 20m Metal 8K Ultra High Speed HDMI Cable 48Gbps — A metal‑jacketed HDMI 2.1 cable claiming 20 m length and 48 Gbps 8K support. Useful if you want a more rigid, durable cable.

• SKW HDMI 2.1 Cable 20ft 8K Ultra High Speed — A shorter but still 8K/48 Gbps cable; note this is ≈ 6 m (20 ft), not 20 m — good if you actually need a relatively long but not extreme cable for your setup.

• ETZIN 20m 8K Ultra HD HDMI Cable — A budget‑friendly 20 m option with claimed HDMI 2.1 / 48 Gbps spec. Worth considering if you want long‑run connectivity without high cost (though performance may vary depending on actual build quality).

⚠️ What to check when buying a 20 m HDMI 8K cable

• Type of cable: fiber‑optic (AOC) vs. passive copper — For long runs (~20 m), fiber AOC cables are much more reliable to retain signal integrity than passive copper cables. Many sources note that passive cables often fail to sustain full 48 Gbps over long distances. 

• Full HDMI 2.1 / Ultra High Speed certification — Ensure the cable supports 48 Gbps, 8K@60Hz, 4K@120Hz, HDR, HDCP 2.2/2.3, eARC etc. Passive or non-certified cables may claim 8K but underperform in real use. 

• Connector & build quality — Strong connectors, good shielding/flexibility, and durable jacket (often fiber + PVC or braided) help in long‑term stability and easier installation in home‑theater layouts. 

If you like — I can pull up 5–10 HDMI 8K / 20 m cables currently available in India, with price in INR and retailer links (so you can directly check what’s available for purchase now).

Do you want me to build that list for you now? / Ultra‑High-Speed) support — useful if you need a long cable run for 4K/8K TV, projector or gaming setup.