Back in February, LinkedIn quietly added a manual alt-text tagging option for uploaded images, helping to improve platform functionality for vision-impaired users, while also, potentially, giving LinkedIn another element to use for related search and discovery options.

With LinkedIn become more visual-focused, the addition makes a lot of sense, and brings LinkedIn into line with other social platforms. And now, LinkedIn has expanded its alt text capacity, with social media expert Matt Navarra sharing this screenshot which explains LinkedIn's new automatic alt text generation process.

That's important to note - first off, again, from an accessibility perspective, and ensuring everyone within your audience can get the most out of your updates. But also in respect to search capacity - with LinkedIn adding alt text for all images, whether you've added them in or not, that will give the platform more data points to refer to when displaying relevant content.
How accurate those auto captions are, and how exactly LinkedIn is looking to use that data, are both obviously significant factors here, but it would make sense for LinkedIn to use the alt text field as an extra qualifier for search matches where possible. If your post is about a car, and LinkedIn can identify a car within the image, that, you would assume, would make the post an increasingly relevant match for those interested in the topic.
We don't know for sure if LinkedIn is looking to use these tags beyond improving user experience, but there are some pretty good reasons why you should be checking in on your LinkedIn image tags, and ensuring the automated notes match the context of your updates.