This comes from a memory of a digression during a lecture in an ecology class I was in 20yrs ago… so you know, grain of salt.

From this particular professors point of view. Symbiotic was the term to describe mutualism until recently. And then. A few papers started using symbiosis as an umbrella term for all relationships with sub-terms to describe the “benefits math”. This, to him, was annoying pedantry. But eventually all the textbooks adopted the new hierarchy of terms and the world moved on.

If you took a biology class with a text published pre-2000s, it’s very possible that your book described symbiosis as a mutually beneficial relationship between species.

Long story short: the language is fluid and ever changing, even in science fields.