We have multiple RSS feeds in Tridion-based .NET websites. The RSS feeds need to be rendered as utf-8 (for content syndications). However, currently, they are rendered as urf-16 in the PROD environment.
If you view the page source in the browser, you will see the encoding is utf-16.
Most feeds are rendered based on broker query results. In some cases, the feed items are managed via a component in CMS. In all environments, the templates/TBBs and web applications are identical except for environment variables such as DB connection strings in web.config. The "preview" (stage) and "www" (live) sites are supported by the same CMS in PROD.
Currently, all feeds rendered via DXA web applications in DEV, QA and Preview show utf-8. But they all show utf-16 in the live sites.
FYI, the feeds in PROD also show urf-8 when debugging in Visual Studio using the localhost. We have Tridion Sites version 9.0 and DXA 2.1.