The traffic was reduced to nothing after Google changed to canonical URL … What can I do?

Hello SEO experts,

Please, forgive me for what naive my question that will sound to the professionals :)

I've been blogging for 15 years. Traffic was still stable or increasing, but it was almost no longer reduced in August 2018. This corresponds to the following:
SEMrush

"
Updated Google Search
An event has occurred in Google Search and could affect your site's data. "

And when I look at the event, I arrive at:

All measurements are now attributed to the canonical URL selected by Google from the page associated with the search results. This means that if a user clicks on a search result with a non-canonical URL (for example, an AMP version or a non-canonical mobile or desktop version), the canonical URL is credited with printing and click canonical URL actually appeared in the search results. This change should make it easier to see the search data for a single content in a single property. You can learn more about this change in our blog post.

I have a hard time understanding what it means and how it concerns me … and what I can do to "satisfy Google".

No advice? Explanation for dummies like me?