The query plan shows us that we got a Trivial Plan, and that Simple Parameterization was attempted (as shown by the 100000 literal turning into the @1 parameter.)
Simple Parameterization is only attempted in a Trivial Plan.
The key word here is attempted.
Normally, you spot the change to your query string, you go in to the properties and you see both (and it has to be both) a Parameter Compiled Value and a Parameter Runtime Value, you’ve got simple parameterization going on.
Or do you?
Notice the final property on the sheet, StatementParameterizationType. Honestly, I never really paid attention to that property. I knew what kind of parameterization I was seeing. I’m not running Forced Parameterization. This isn’t a parameterized query. It’s Simple Parameterization. Of course it is. All the keys are there. Change to the code. Parameter List values. Done.
Narrator voice: it wasn’t done.