Challenge: Identify Grammarly Users Without Referring to Grammarly

The easy thing to do is to install Grammarly, note its solecisms, and then naturally recognize those solecisms to identify Grammarly abusers. Too easy. The proper training exercise is to figure out someone is using Grammarly based on a hunch, and subsequently validate the conclusion using independent indirect evidence.

In particular, Grammarly loves hyphens. (That was my google search for the confirm.) It will give you one-hundred ways to incorrectly use hyphens. ("Also note that “semicolon” is not spelled with a hyphen") At least a hundred of them. Whatever a [one-hundred] solecism is.

"but he’d decided to avoid any half-measures and go full-ringwraith." (Delve ch 61) As opposed to full half-ringwraith or quarter-circle grass-type-ringwraith. See, Grammarly, if you really love hyphens and want them every-where, you don't have to use them un-correctly.
"there’s not a damn thing I can do to stop her, short of moving-in with Halgrave" A good joke: an alleged grammar-checker can't detect context. Thinks all instances of moving and in are from moving-in day. What's the difference between a moving-in with Halgrave and a regular with Halgrave?
"He’d lost his foot to something called a ‘dunch’ early-on in his career" Presumably that's the opposite of a late-on. I wonder if a late-on also has a dunch variety, or if they're solely chwemp. Must be quite the energetic ion if it can take off a whole foot.

Alternatively it could have been a wonderful new decay fad, such as using 'dismantling' when they mean skinning and butchering. As expected, idiots are seeing bad translations and 'improving' their writing to the bad translation's standard. Have a bear you want to process? Get out your wrenches and screwdrivers, we're gonna dismantle it. First, unbolt the skin, then carefully lever it away from the muscles... I suspect the every day / everyday failure in Harvest Moon GBA was patient 0 for that error.

Instead, many alleged EFL students are telling on themselves, because the Grammarly style is impossible to miss if you even vaguely know what you're looking for, as expected. Grammarly clearly noticed that stuff like twenty-two takes a hyphen and decided that numbers love hyphens just like it does. (To distinguish it from twenty twos; it was originally twenty-and-two.)

Alternate alternative, Grammarly could have offered good grammar advice. It shouldn't be logically impossible. Merely empirically impossible. Instead, Grammarly will actively degrade your grammar unless what you're starting with is so unreadable it's Canadian-Healthcare-tier.
Not unlike Strunk and White, come to think. Or that 1800s grammar book that told everyone they had to use [he] instead of [they], which inevitably lead to the cancerous [he or she]. Negative-sum grammar checkers are traditional at this point. Lindy, even.