The way nutrition science works is that there are mainstream guidelines which are approved by consensus, which are repeated constantly and sometimes have become outdated or wrong over time, and arent not changed despite new information. Either because of corruption (people making money off a certain industry or lobbying, or nefarious plots) and because of beaurocratic inefficiency.

On the other end you have "people's medicine" which runs the spectrum of cutting edge real health science like microbiomes effecting mental states, to insane bullshit like sunning your testicals and eating raw meat.
It all takes a discerning eye and a willingness to research things yourself.

Generally healthy fats are minimally processed, like butter (sparingly), fish oil (from eating fish) olive oil (cold pressed) and other healthy fat sources like nuts and avocados.

Seed oils (canola, soy, etc) while still unrecognized as "bad" by the mainstream are being shown to have many long term negative health effects due to the processing, and its been revealed in recent years that what was and still is considered "healthy oils" by the mainstream have created more heart disease than the foods previously thought.