Hi, welcome to the forum.
Your decanter is certainly going to have been cut as it looks like it…but hard to explain why

If you handle some pressed glass it should be relatively easy to see and feel the difference. If you use a strong magnifying glass you might be able to see the fine grinding marks going along the cuts (if it hasn’t been very heavily polished) and sharper edges.
It looks like a reasonably good quality example as the handle is quite fine and nicely cut too, the faceting around the edge of the foot isn’t very common either. You can see that the handle isn’t moulded as it has been applied at the bottom (where it is fatter) and drawn out and then stuck on at the top (where it is thinner).
The decanter looks relatively modern to me (vintage rather than antique), you could try searching replacements.com for a match if no one recognises it. Sometimes an acid stamp manufacturers mark on the bottom can be very hard to see, so it’s worth having a very good look.
On a bit of a negative, I’m not sure the stopper matches the decanter. In the photos the spherical top looks quite large compared to the body of the decanter. Possibly the plug part is sitting a bit high in the neck too, but it’s hard to see. It’s possible that the stopper is a replacement.