They come back in stock almost every week, keep an eye on https://rpilocator.com - and maybe subscribe to their twitter if you want instant stock alerts.
Chiming in to say that if you're using this to buy a Pi from AdaFruit make sure to register an account with two-factor auth before you get the chance to buy. They require this to deter scalpers, and they'll run out of stock before you're able to finish the process if you haven't already done so.
I just checked and as if by magic, yep, there are some CM4s (in Germany). I've been looking to pick up a couple more Zeros though and haven't seen those in stock in months.
It's my understanding that the Zeros are very low priority for production, so you might be waiting a while for those. Since you're only allowed to buy one per order anyway they're not actually that useful for much.
