I'm trying to understand [this post](https://www.wasabi-jpn.com/japanese-
grammar/japanese-adjectives-with-particle-ga/) on using Japanese adjectives
and am stumped by this paragraph under the I-adjectives section

> When you use i-adjectives as a subject complement, you MUST NOT do the same
> thing you do with na-adjectives. The variety of form is called
> “conjugation.” Using conjugation in place is significantly important when
> learning Japanese.

I have absolutely no clue what it is referring to by 'the same thing' and
would appreciate any explanations
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2021-10-18T02:15:54.637
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question
conjugations adjectives i-adjectives na-adjectives
What does this paragraph mean in Wasabi's "Japanese Adjectives with Particle が" article?