That is a question! What event of 2021 influenced content marketing the most?
The only answer ic coronavirs pandemic!
Although it lasts another year, it cannot pass without a marketing echo. You can still see references to remote and / or hybrid work in the content. Many widely promoted mass events have moved online, because 2020 has shown that it can also be done this way. And it is quite effective. Social media has returned from purely advertising content to its roots: social media.
Challenge: Unpredictability of pandemic development and lack of knowledge of governing plans as regards restrictions. Inability to plan content marketing in advance, which quenches the enthusiasm of both contenters and recipients.