Data:
Social Media data sourced from Infegy, a consumer intelligence platform that collects, analyzes, and visualizes billions of social media posts.
Polling average from FiveThirtyEight’s summary of Joe Biden’s approval rating, available here: FiveThirtyEight- How Popular/Unpopular is Joe Biden?

Explanation:

This visualization tracks the aggregate average of online sentiment for posts across the internet discussing Joe Biden from January 1, 2021 through the present (n=74,409,409 individual posts). I compared that with the moving average from FiveThirtyEight’s How Popular/Unpopular is Joe Biden?
The original idea for this graph came from a Politico article that said that after the Taliban’s takeover of Afghanistan, Joe Biden’s popularity began to slip (Politico - Biden's Afghanistan Withdrawal Anniversary).
Interestingly, it looks like aggregate sentiment data form social media bears that out to some degree. Biden’s sentiment online drops as the Taliban began their advance. That drop in sentiment is matched with a drop FiveThirtyEight’s polling.
Overall though, it appears that social media data is more reactive, but less durable than traditional polling. Negative/Positive stories break in the news, which causes sentiment to go up or down.

Tools:
Python (Pandas and Matplotlib)

I wonder how much of this you could attribute to herding in daily approval rating polls that are released by polling organizations. I know it's something 538 and other polling aggregators and observers have been talking about on an ongoing basis, so there's probably no full answer, but I am more curious if it is more "real" to have more variability day to day.

Yeah, that was a tricky bit. 538 often has longer type polls (e.g. this poll is valid from 10/1- through 10/5). To handle those, I just took the beginning of the date range.

It’s just possible that social media comments are not fully representative of actual adult non-bot American registered voters.

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Since 538 doesn't do polls, I feel like the "538 poll" data points should be named something else.

this, for one

How can you even claim to guarantee that? Even you didn't assert that it wasn't a problem. You said 'I'd guess they're fairly minimal'. That sounds a lot like wishful thinking, not a result based on research and statistics.

This is good feedback, thanks!