Not all Hashtags are the same. Powerful hashtags in Instagram may fall flat when used on LinkedIn.
LinkedIn's hashtag search is not very well developed. You can perform a hashtag search in the feed and that will give you relevant content that is using the hashtag but does not provide the popularity, specifically the number of people following a particular hashtag. They best way to determine hashtag popularity is to type it directly into a modified LinkedIn URL - such as: https://www.linkedin.com/feed/hashtag/marketing/

Changing the URL to https://www.linkedin.com/feed/hashtag/digitalmarketing/ shows that there are currently 7 million more followers:

How to find relevant hashtags on Instagram
https://www.linkedin.com/pulse/only-article-you-need-read-linkedin-hashtags-joe-gannon-