How did this competitor get so many referring domains/backlinks so fast?

I was looking at a high ranking competitor's data in SEMRush and noticed their referring domains and backlinks both spiked, though at different times. Linking an image of the data in the comments since the automod removed my first post. My initial inclination is to assume that these links were paid for. When looking at their referring domains and the quality of the links themselves, they are very clearly low quality links. But this begs the question: Will a sudden burst of low-quality backlinks really tank a site per common guidance seen on this sub? Because this site is doing phenomenal in ranking for many different keywords within this particular industry, even with significant competition.