Since I checked on this topic too, I'll provide my latest findings:
According to the magento 2 docs:
"The Magento application has a default cache frontend you can use for
any cache type."
This means, that you can specify all cache types in the cache->frontend section of the
If you check out the cache types you'll notice that there are more than just the "default" and "page_cache" types to set.
Although, according to https://www.mageplaza.com/:
"The default cache segment enables you to configure all cache segments
except for page_cache (the full page cache)."
This means, the default type covers the following data:
and the page_cache covers the
To cover your question, since I'm not sure what exactly your patch did, I assume, that either the patched content was still in the
full_page cache or maybe part of the
I suggest, that you clear all caches after a deployment in any case, to get rid of old artifacts still floating around in some cache. This will prevent confusion and debugging times if something old is still there, but should not be there anymore.