Sysadmin Attack to /search?Q=

Hi everyone, I have been receiving links from unknown sources for a month now pointing to: /search?Q=
Site based on Wordpress.
The site returns error 404.
The problem is that there are thousands of links that google robots keep visiting, obviously I have hundreds of reports in webmaster tools.

this is a complete example:

Code:

www.domain.tld/search?q=카지노+룰렛〖〗『gmvcs.com』바카라+썰무료+카지노+게임Y⇇◑2019-03-06-10-11⇩AIJ⚘바카라사이트추천바카라+중국점+보는법온라인바카라사이트⊙에프원카지노☐온라인바카라게임⇛

Have you ever received traffic like that?
The origin ip are related to semrush bot, google bot,

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Solutions?

 

the problem is not so much the bad bots.
I have verified all the IPs that land on these pages and are search engines, Bing and Google certified IPs.