Identification of the simple subject in a sentence

"Simple subject" is not a valid concept.

It means a single word that the teacher can point at. It isn't the subject, which are normally full noun phrases, with modifying determiners, adjectives, phrases, and clauses.

Everything that comes before 'is' in the example sentence is the subject of the sentence; it's a noun phrase with a modifying reduced relative clause.

Don't ask about the "simple subject" because it doesn't exist.

-John Lawler

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In a now-deleted comment, Cascabel said...

..."journalism" here is part of a reduced relative clause modifying "problems" ....definitely not the entire subject; just part of the Noun Phrase.

If "journalism" were the actual subject, it could be read as...

"Journalism (today) is false news and disinformation",

which is possibly a true statement when applied to some news sources these days, but obviously not the intent of the writer.

To summarize...

Identifying a simple subject in a complicated sentence could be compared to applying Bohr's model of the atom to an E8 lattice structure.