This is probably obvious to most of you but Google's John Mueller said on Twitter that Google does not index redirects. Meaning, if you redirect page A to page B, any content that might be on page A is not indexed, instead GoogleBot just does a hop, skip and a jump over from page A to page B. John said "We generally don't index URLs that redirect, so that seems to be working fine."
Here is the context:
We generally don't index URLs that redirect, so that seems to be working fine.
— 🍌 John 🍌 (@JohnMu) November 19, 2018
Bing works this way too, even with 302 redirects, which is also logical.
Forum discussion at Twitter.