Consider the little word curb;
It’s used as a noun and a verb.
Appetite or enthusiasm
Or or a bad muscle spasm,
It means to control or disturb.
A curb is a physical restraint;
With that use I have no complaint.
Curbside pickup or check-in,
Correct uses without reckon
But “a steep learning curb” it ain’t!
Note: Learning curb is a good example of an “eggcorn.” Have you more to throw into the basket?