Fantasy 1910 George V Double Florin

Likely Chinese as they're for sale on Aliexpress.

Anything that looks a bit odd, often worth doing a quick search there. Sadly there aren't any guides or lists of copies. It's just a matter of experience. For what it's worth, the bust is completely wrong. A second hand copy of Spink's Coins of England would show you what they're supposed to look like, if you don't have one already?

The "DRG" initials indicate these coins are modelled on the portrait of George V by Donald R. Golder. In 1999, the London-based International Numismatic Agency (a medal and fantasy-coin maker) commissioned Golder to make portraits of former British monarchs for a series of coins that they planned to make but never issued; in 2001, Spink purchased the designs of the portraits and issued a series of "fantasy patterns" using the INA designs. They were marketed by the Spink under the name "Patina Retrospective Pattern Collection"; you will also see them called "INA fantasy patterns", which is what the slabbing companies call them. Yes, the slabbing companies will slab (genuine) Spink fantasy coins; they are also listed in the Krause "unusual" book.

The INA/Spink fantasy patterns were struck in various metals, but always to cameo-frosted proof finish. The OP's "coin" is not a cameo-frosted proof, and never was. This one also bears the hallmarks of (yes, sad to say) the Chinese mass-produced fakemakers, in terms of slightly askew legends and portraits that are almost, but not quite, entirely wrong.

Yeah, I for one would never buy any coins coming out of China or Hong Kong. Anything you buy these days have to be looked at very closely.