Someone (not me, obviously) created 100,000+ different links to the root page of my website, by using a bot, from 100,000+ different pages of the edition of the Wikipedia of a country (in the minority language of that country, my website is in English).

Could this action damage my SEO? If so, any idea to remove all the links?

My website has 1,000,000+ webpages, I submitted them to Google through Sitemaps, but only 200,000 are indexed. Additionally, I'm suffering the Google sandbox effect, with pages which actually offer high-quality information for several searches, but with very low ranking within the SERPs. Could both events be related?

Thank you very much.