They would say that, wouldn’t they?
“STP” and “ECN” and “NDD” are terms invented to fool you.
None, now - I trade forex futures, so my broker is always on my side and wants me to win, not to lose.
(I used to use them, a long time ago.)
If you need to use one, just choose an honest, low-leverage one and make certain BEFORE sending funds there that YOUR ACCOUNT (not just the broker) is regulated by the FCA, ASIC or CFTC/NFA. That’s what matters. There are a couple of lessons covering this in detail and explaining why it’s so important, in the free course here, and reading those carefully will also help you. (And honestly many of the other lessons there would also help you a lot, regarding many of the other questions you ask here.)