24k backlinks on 8k pages on our partner's website using the wrong link?

We changed our Italian site from a subdomain to a subfolder to better manage all our sites.

In the 20 or so years we've had this site, our partner has used our subdomain address until now.

it dot hello-random-site dot com --> hello-random-site dot com slash it

Our crawl budget for Google bot has dropped significantly, -78% to be exact, over the past year. Nearly all of our pages have 200 minus a few images that we axed. A few 301 (20%) however we have no redirect chains exceeded 3 links. SERPs are very low with a page 7.5 average for money keywords if at all.

I have a reason to believe that with that many backlinks from one referring domain using the now wrong URL on all its pages, it'll be causing some crawl delays and budget waste.