Can you tell us the exact steps you did when you tried the trainer yesterday?
Me and many others used it excessively and didn't get any shadow ban or permanent ban from that...
Did you injected the trainer into the game? Did you close the injector before opening the game? Did you had the BattleNET client app open while injecting? The tool itself is pretty save as it hijacks another programs memory. My guess would be you entered a multiplayer match while the trainer was still injected and got flagged. I heard about that back in BO4 where you could use a tool safely in Zombies, but when you entered a MP match while it was still injected you got a delayed ban...
Also, when did the shadow ban come active? What was the delay between using the tool and the ban being enforced on your acc?