Netflix (the N in FAANG) uses device-appropriate codecs and formats, and defaults to AVC (H.264). Googling around shows they provide HEVC (H.265) streams to at least some devices.
Netflix do use HEVC, mostly because there isn't any other solution for high quality 4K streaming in Apple ecosystem. They use it out of absolute necessity. They have been vocal supporter of AV1. And their ex-Head of Video Encoding which now works in Facebook has a distaste for MPEG video, although that is admittedly HEVC and VVC. Everyone seems to be (mildly ) happy with AVC.
Netflix on a recent android mobile showed that the formats supported for hardware decoding are h264 and VP9. So, thought the mobile doesn't have h265 h/w. But then installed mpv from fdroid and played h265 video and mpv said it's using h/w decoding. So for some reason, Netflix chose not to use h265.