You are 100% correct, there is no such thing as a 4TB SD card. Largest you can get is 2TB. Western Digital has shown a 4TB MicroSDUC and even 8TB SDUC card at shows and events, but I don't think it has found its way into production just yet. And with the extreme prices of flash these days, I doubt they will release it any time soon. The 4TB card would probably be $1500 - $2000 retail, who is going to buy that? And what is the use case?

The picture is some mockup someone made or maybe AI generated, but not of a real card.