Is this negative SEO? Sudden increase and decrease in backlinks

Hey guys,

Recently, our page saw a very rapid decrease in organic traffic and SERPs. While I do understand that this could be a cause of Google Core Algorithm updates, but I have noticed, that starting from March, there have been 4K DAILY new dofollow backlinks from random sites , up to April, when these new backlinks were "lost" (4K lost backlinks in a day) up until June.

Could this be the source of traffic/position decrease? How can I stop these backlinks? Can this be a signal for Google to flag our website? Could this be negative SEO? Should I be worried?

I would appreciate your input.