on weekends - "at" and "on" are both used. The former in British English and the latter in American.

risk, but.... - shouldn't this be one sentence.

et al., "al" is an abbreviation and should have a period.

Extra word

I looked online and most articles capitalize "white" in Black/White binary. Those that did not, had "black" in lowercase along with white. https://lawcat.berkeley.edu/record/1115988?ln=en

ones, like Amazon, require

I think it might look better to use the entire word instead of the abbreviation.

Why not just write out the entire word to avoid possible confusion.

I found this statement confusing. "The author describes the poster's imagery, typography, and what the poster denotes" or are you saying the author describes the imagery and typography to explain what the poster denotes.

You may want to capitalize the "l" which is the American rule, the British rule does not.

The font is smaller on this one section.

"A colon is not normally followed by a capital letter in British usage, though American usage often prefers to use a capital." http://www.sussex.ac.uk/informatics/punctuation/colonandsemi/colon

There is an extra space here.

This would be considered an unnecessary filler. https://www.bkacontent.com/avoid-overusing-word-writing/

The word that here would be considered an unnecessary filler. See the rule below: "To decide whether you can omit “that” from a sentence, check how naturally and intelligibly the sentence reads without it. Usually, you can drop “that” if it follows a verb that essentially means “to say.” This omission mimics natural speech and shouldn’t change the meaning of the sentence.

The children claimed an ice cream break would help them study more effectively.
She insisted she wasn’t responsible for the houseplant’s untimely death.

However, it’s usually better to keep “that” if other words fall between the verb and the dependent clause.

The kids also said this morning that a television break would enhance their studying.
She admitted begrudgingly that she might have contributed to the plant’s demise."

Extra period