Yannick,
Your credentials should still allow you to log into my site:
https://www.example.com/administrator/
I was curious in that in the Recorded Errors section of 4SEO there are a lot of images that are in 404 status. At one time I used a scraper of sorts to bring news articles to the site, but that has been gone and deleted ages ago, but I see quite few images from that system in the list "images/obgrabber/2018-05/80079f2e9d.jpeg" for example. Anything in the obgrabber directory shouldn't be referenced on my site, is this from other sites referencing my site? Same would go for stuff referencing Phoca Gallery, haven't used it for some time: "images/phocagallery/interior/thumbs/phoca_thumb_l_int33.jpg"
Could be all of this would go away once I removed Jsitemap Pro as it has been on my sites for ages and maybe it has caused this, I will get around to removing it soon.
Thanks in advance for your time.
Best regards,
Russell Thomas