After cleaning SRAM AXS rotors and pads (organic) with isopropyl alcohol, the brakes always need bed-in (maybe for a shorter time than new brakes, but they still need bed-in). Is this normal?

What happens that makes you think you need to bed them in?

I'm still on my first set a brake pads. 8000 miles so far. Haven't bedded them in ever. I have occasionally cleaned the rotors with alcohol. Though I'm Shimano 8000 series, not SRAM.

Very poor brake performance after cleaning. Furthermore, if a sudden hard brake is needed soon after cleaning, the brake is noisy an it shudders.

So from bed-in you mean actuating the brakes to deposit a layer of brake material on your rotor. Hmmm...?

So you are bedding in brake pad material onto a rotor you just cleaned off? Right?

Sounds logical, but what do I know?

So many questions...

Sometimes certain things can contaminate your pads. And there is nothing you can do to effectively clean them. Though there are plenty of remedies that others claim anecdotally that solved their issue. You can look and try them if futzing around with such is what you want.

I'd make certain the rotor is within whatever limits SRAM specs for it. And then get some new pads. And if a new rotor isn't a burden for your wallet, go ahead and replace it too whether the old one is worn or not. Make sure that the pads you get are for the rotor you get. Some rotors aren't made for certain types of pads, resin, metal and etc.

There is no contamination or deep wear and new genuine pads from last year behave the same. I am in course of changing SRAM pads with compatible Swissstop and I am just checking my understanding about how disk brakes work.
Bed-in seems to result, indeed, in depositing a layer of pads material on the disk, which improves braking performance. My understanding was that bed-in is done once for the whole life of the pads, but my SRAM rotors seem to lose pads material every time I wipe them with alcohol, then need to repeat bed-in.

Depends on the pad material. With contaminated resin pads you're essentially SOL. With fully metallic pads however it's easy to just burn off any contaminants, either in an oven or with a hot air gun.

If your brakes stop you well enough, I'd say there isn't a need to bed them in. I just let the course of normal stopping bed in my brakes. It took 200-300 miles before that happened. Perhaps if you cycle where you have to make a lot of stops, that will happen sooner.

If your bedding procedure involves coming to a full stop or causes your wheel to lock up. Then you are doing it wrong.