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If it was done correctly and systematically, the effect may be minimal.
Here's a rundown, expecting you are using a custom domain since that you mentioned you have an active Adsense account...
1. Download your WP blog contents.
2. Convert the WP file to Blogger XML file format.
3. Create a blog or use an existing blog of yours on Blogger
4. Upload the new contents at #2
5. Prep the new blog, check the page and posts contents, check the meta data like search description etc.
6. Detach the custom domain pointing to WP servers & point to Google servers. Here's how: https://support.google.com/blogger/answer/1233387?hl=en&ref_topic=6321959
7. Assign the domain of yours at your Blogger Settings.
8. Use Custom Redirects to redirect your WP pages/posts urls to the new urls created for the upload contents at #5
9. At Search Console, submit your new sitemap
10. Wait for re-indexing, might take days to weeks to months.
11. Continue to publish new unique contents consistently - it helps!
It might be a bit hectic if you have hundreds or thousands of published posts in WP as we have seen reports that large contents files not able/unstable to upload to Blogger servers.