This is an open question. Traditional passive HDMI 2.0 cables made of shielded copper wiring can extend to 20 or even 30 feet in some cases. As for active fiber optic HDMI cable, the BONESTEC’ unique AOC+™ technology does help the signal to be transmitted up to 150meters maximum.  

At 48Gbps data rate, the best passive HDMI 2.1 cables can reach 10ft before they run into difficulties. That’s fine for the average living room setup, connecting your new Xbox Series X, PS5, or RTX 3000 graphics card to your HDMI 2.1 TV, but you’ll need an active cable to go further if you want to maintain the full 48Gbps bandwidth of HDMI 2.1

what is the maximum effective length for fiber optic cable?

HDMI cable length for active HDMI 2.1 connections can increase dramatically whilst retaining full bandwidth. An active HDMI 2.1 cable can measure up to 25ft without difficulty, giving you much more cable reach to play with. That makes it possible to set up an HDMI 2.1 TV much further from the 4K or 8K source.

At the very high end of active HDMI cables, you also have the option of HDMI 2.1 active optical cables. They offer the highest protection against signal attenuation, therefore letting you run the cable even longer. The best fiber optic active HDMI cables max length can over 35ft or even 50ft and 100ft and still maintain the full bandwidth of the HDMI 2.1 cable standard.