ITC Avant Garde Gothic Extra Light

It's actually somewhat common for type families hosted on the Adobe Fonts service to be incomplete compared to the retail versions of the same type families. Some weights may be missing, as is the case with ITC Avant Garde Pro. In other cases the typeface may have a more limited character set. I noticed this with the Mislab type family; its retail "Pro" version has a bigger character set that includes true small capitals, the "Std" version on Adobe Fonts has a more basic character set.

At least with the 3 weights of Avant Garde Pro on Adobe Fonts they have the larger "expert" character set with a huge number of two charater ligatures in uppercase and lowercase ranges. Other versions of Avant Garde that have been bundled into some graphics applications (CorelDRAW, Canvas, etc) don't have those cool extended character sets.

The differences between type families hosted on Adobe Fonts versus the versions for sale really comes down to whatever agreement is made between Adobe and a type foundry such as Monotype. And Monotype is a monster-sized company compared to other type foundries. They've acquired so many type libraries over the past 30 or so years (ITC, Linotype, Berthold, Hoefler, etc). Monotype is also promoting their own subscription type service, which sort of competes with Adobe's service. If anything were to change I'd be more concerned Monotype might remove some of the 41 type families they're sharing on Adobe Fonts.