Database being hit with thousands of (Google?) search queries causing high load

I have a bit of a strange issue. Running this WordPress site several years now, but never encountered anything like this. LEMP server (ubuntu, nginx 1.18, mysql 8) Two weeks ago (according to Google Search Console excluded noindex pages and me manually checking mysql processes), more and more hits to the database started to occur (now already 4M+). All very similar (search queries?):

SELECT COUNT(*) FROM xx_posts WHERE 1=1 AND (((xx_posts.post_title LIKE '%google=662496898\_session/feed/rss2/<a_href/page/3//page/1/&usg=AOvVaw1w32-jX45qQEhTH-iBghzF

The part after rss2 tends to change. No idea where this is coming from, but it seems to be increasing and causing the server load to increase as well.

Has anyone seen this before? Or hints to find where this is coming from? No new plugins or themes were installed in the past few months. Everything is up to date.

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