Truth About Diminishing Gains!

I know that ALL gains diminish over time. But do natural gains and gains
made on 1 cycle of steroids (after proper pct) dimish at the same rate
when not working out?

For example, a person does one cycle of steroids and after PCT retains 15lbs
of muscle. Now, they continue training for another year and after that year,
are unable to workout for a 6 month period for whatever reason. Would they
lose muscle at the same rate as if they were natural during this six months,
keeping in mind a year has passed since the cycle. Does the body begin to treat the muscle reatined after PCT on steroids as natural?

I have gone 6 months without training and have only lost 2-3 lbs of muscle.
Would I lose at the same rate during a six month break a year after cycling?
I'm not asking this question because I want to take a 6 month break, I just
want to know whether the body treats muscle gained on steroids after PCT the same as it would treat naturally gained muscle in regards to diminshing rates?

Please keep in mind I am only talking about 1 or 2 cycles.

It also depends on where you start. Someone already massive will have lots of trouble keeping gains naturally after a cycle. The rate at which you make the gains (lbs/wk) in addition to your diet and training subsequent to the period of "gain" will be what's important. If you're a year post cycle when you stop, your body doesn't have any way to determine by what means your gains were achieved. You'll have reached a new "set point" by that time, and the mass will be lost without regard to how it was gained.