There is no inherent technology difference in light sources between miniLED and regular FALD TVs. It's just that mini LEDs generally have smaller LEDs to fit more of them to get more dimming zones. However, it's not a strict rule. You can call any regular FALD TV a miniLED and no one can claim otherwise because there is no strict number or technology difference (correct me if I'm wrong here)
This is what TCL is doing. Calling a regular FALD as miniLED to gain marketing advantage. Also, C825 has significantly fewer dimming zones than their R635 (Which is a 6 series mind you) and Q825 from 2019. The only difference is that those TVs are only available in US and these overpriced ones outside US.
BTW, this is from TCL which itself says miniLED should have about 1000 zones:
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