Her channel has been in the same style as Zoella since the very start. It was probably always her dream to post mundane everyday chitchat and have people comment on that. However she also realised that people don't click on vlogs that have boring titles and they definitely click on ones with a very distressing thumbnail and something about cancer. The ratio of cancer vs fluff content is increasingly skewed now...usually only 2 mins out of 22 are relevant to the title and doesn't go in depth. In the latest video the thumbnailing implies she will talk in depth about letters (plural) from the hospital but it was basically just her reading a single Whatsapp message telling her family the genetic test was negative.
The problem is that she's much more prolific than other cancer vloggers. On other channels, at least 80% of the video is dedicated to health updates and there is generally only an update when they have enough news to fill a video. By uploading twice a week with Instagram and Shorts in between, it's virtually impossible for Tiffany to find enough content to fill the videos that are still fully relevant to her health journey. And she's clearly decided not to disclose a number of things (eg. previous surgeries) which affects her viewers getting a fully transparent image of the situation.
To be fair, it's her channel so she can obviously upload whatever she likes. Her long-term goal is probably not about being a cancer channel but to make money on Youtube posting everyday stuff like Zoe Sugg. She's hoping enough people who came for the cancer videos will stay for the vlog stuff and it seems to be working. Many viewers seem to enjoy the chitchat and she does have a pleasant voice and style on camera. It's basically not a channel for anyone wanting in-depth discussion about cancer (eg Romee Dussenbrook, Jenny Apple, Krocks in the Kitchen, Eamon and Bec) but an everyday vlog channel by a creator who happens to have cancer (or based on latest info, had cancer).