Using that global variable was a bad idea. Stick to redux as the source of truth.
The flag is not listed for rehydration, so it will always start off as `undefined`, which is what we need anyways.
`undefined` indicates we haven't tested for ad-blockers, so we'll run the fetch and update the store with a true|false value.
## Behavior in homepage
- Mobile: show after every other category
- Desktop: show after first category, then every 2 categories.
## Known issue:
- "FYP" is not part of the categories array at the moment, so it does mess up the behavior.
## Notes
I think this is also called "in-content" by adnim (not 100% sure of the terminology).
