Google Search activity cards are not new, they've been in testing since 2018 and launched in January 2019. But Google has upgraded them for shopping and product searches, job searches and recipe searches. Google said they have "updated them for shopping, jobs & recipes, to show you related and new information."
Shopping Activity Card
The shopping activity card will show you products you’ve been researching, even if they were featured in an article you were reading.
Here is what this one looks like:
Recipes Activity Card
The recipes activity card can now show you even more relevant recipes related to your query. If you have searched for chicken recipes, Google will show you the related recipes you’ve recently visited and provide a thumbnail preview to make it easy to select the right one.
Here is what this one looks like:
Jobs Activity Card
Many are looking for jobs in this time and the jobs activity card can now show you new, relevant job postings since you last searched. This way you’ll quickly know if there are new opportunities to explore instead of scrolling through old postings.
Here is what this looks like:
Forum discussion at Twitter.