Learn Italian: Il pettegolo ha provocato clamore sia ieri sia oggi. - The gossiper caused an uproar both yesterday and today.

The word pettegolo can be an adjective meaning "gossipy" or a noun for the person who gossips (the "gossiper"). If you want to talk about the actual piece of gossip or the rumor being spread, you must use the noun pettegolezzo.

Why do we use sia ... sia here instead of a word for "both" like entrambi?

When linking two distinct elements to mean "both X and Y," Italian uses the correlative conjunction sia X sia Y (or sia X che Y). The word entrambi means "both" but is only used when referring to a plural noun as a single group, like entrambi i giorni (both days), not for listing separate items.

Could I use causato instead of provocato in this sentence?

Yes, ha causato clamore would be perfectly understood. However, the verb provocare (to provoke, trigger, or bring about) is a great B2 vocabulary choice because it pairs naturally with words denoting strong reactions or public noise, like clamore (uproar).

This lesson is about limitative clauses. How would adding a phrase like per quanto ne so (as far as I know) change the grammar here?