Sudden drop in my website rankings

Hello,

Since April 14, 2023, we've experienced a sudden drop in our website rankings. We had always been in the top positions for 3 years on our main keywords.

So I can't figure out what happened. Is this an algorithmic penalty because I didn’t receive any notification for a manual action? Is this a bug or an update on Google?

For privacy reasons, we wish to keep our website anonymous.

To help you understand the situation, below is a list of important points and facts :

• Our content is 100 % unique. It's High-Quality content written by a professional editorial team.

• Our health score on several tools is still over 85%. We have reached 98% on some of these tools.

• Our authority score is very good compared to our competitors.

• Our backlinks are of very good quality. They are chosen carefully. We always keep an eye on our links and disavow any toxic or low quality link.

• Due to a dishonest competition, we have been receiving many DMCA Takedown requests since July 2022. For each request we made DMCA counter notice and these are generally successful.

• These fake DMCA Takedown requests became several and regular in March / April 2023. So, for the second time ( First time in July 2022) all our pages have been removed from Google search results. After making DMCA counter notice our pages are restored and our website is on Google search results again on April 12, 2023.

• We recovered all our urls with their first positions. Everything was back to normal until April 14.

Now let me explain the current situation :

• All of our pages are indexed. If we put “site: our website” all the pages are there.
• This is a ranking problem : There are pages on the 2nd, 3rd, 6th, 8th … page of Google search results and others that we can't find even on the last page.
• As already mentioned, we were always in top position for all of our main keywords : We are a service company so our main keywords are in the form of “service name + city”.
• By using this query we cannot find our pages on the top results but we can find their images at first on Google Images search.
• And by using “ Our brand name + city” the pages come out in first position without any problem.
• Our competitors have not been subject to this inconvenience. However I saw that a website under maintenance is ranking in first position. Is this normal ?

So if any of you can help us to detect the problem. I'll be thankful.

Thank you,