When I talk to my peers, the original statement is some version of: "big tech is the most harmful monopoly in the USA today". Saying "what about monopolistic industry x?" is directly engaging with that statement.
It's possible that I'm conflating people's decisions to prioritize talking about tech companies with their actual priorities for which industries require government intervention.
This is an article about the justice department potentially bringing antitrust charges against Google and you made a top level comment saying “what about this other industry?”
This is whataboutism. As clear as the day is long.
I think my interpretation is reasonable, but I get why it's whataboutism in a discussion of the topic "is big tech monopolistic?".