The 25x number already includes this effect. Methane is much much more potent than CO2, but since it breaks down rapidly then over the course of a 100 years the average effect is 25x.
So: if you first say "25x" then you cannot say "break down" afterwards because that is included in the 25x, you are then mentally including the breakdown twice.
There are also higher numbers in use than 25x that is used for the effect over shorter horizons. But 100 years seems like a good horizon for the humanity getting through the crisis or not.
If you are concerned about global warming, swapping one thing for something else that has a greater negative impact is bad.
Having a process or animal that converts CO2 to methane is not neutral just because the CO2 was already in the atmosphere.
> How potent
25x more.
> and in relation to what,
CO2 over a period of 100 years usually.
> and in what amount?
Any amount, it's a relative figure.