This is something I also did in the past. I would “ankify” the books I read, hoping to maximize my retention of the material.

However soon I ran into some problems, turns out I couldn’t remember the cues. The same way you can’t remember the capital of a country if you don’t remember the country itself first!

This led me to question the actual value I was getting from this whole ordeal.

I find this happening over the long term (3-5 years after adding) too, but I think of it as more of a feature than a bug. Anki significantly extends the amount of time concepts stay in my brain, but it's unrealisting for me to expect it to do so over a decade or more without my interacting with the source material outside of simply flashcard review.

If you're not getting value from remembering a thing, it's more about the choice to memorize the thing than how you remember it, seems to me.

Thank you for the perspective. Perhaps because I occasionally, but not obsessively, review the material it stick better for me.

Did you also create reverse cards? Like: Whose contry's capital is Uagadugu?

Anki supports Cloze Deletions, so you could have a card e.g. The capital of {{Burkina Paso}} is {{Uagadugu}}. Anki would then automatically present you with two questions:

  The capital of Burkina Paso is ____.
  The capital of ____ is Uagadugu.