I think the reasonable solution is: Buy a new TV.
We're not talking about a jumbotron display here. A cheap new TV with proper color is likely very inexpensive.
If you want to dedicate that time to improving the planet, avoiding the waste of one TV is likely not a better use of your time than e.g. fixing some bug in some popular open source software that causes it to be less efficient.
Let's say you make a change to Firefox that makes it use 0.1 Watt less on average, and let's be conservative and assume the ~350 million Firefox users use it for one hour a day on average. That's 35 MWh per day saved. Assuming 0.1 kg CO2e/kWh, that's a saving of 3.5 tons of CO2e saved each day.
But the knowledge of how to create a custom shader is going to come in handy one day. More and more I am finding, most knowledge comes in handy some time. You just have to remember at the right time what is possible and go refresh your memory on it.
If everyone spent 2 hours a year removing washed up waste from the beaches, it would have made a big difference.
Saving the monitor, releasing the diy reduces a (minor) head end of the problem that is not only leading to long waste in a landfill, but also metals and plastics in water.
(And who is even to say your bugfix would save power? It's not like Firefox has a power-usage detector in their CI pipeline.)