Domain with 19 backlinks - DR 51. How?

I recently came by a domain with only 19 registered backlinks, yet the DR is 51.

When checking out the links individually, only one.com and a few backlinks of average value show up.

The DA is 5 and PA is 11 for the site.

How is this possible? It seems strange that a website should have such a high DR rating with only 1 really strong backlink and a few average links. Is this most likely just a flaw in the algortim?

must be dem linkz from aliens

Culled/reduced the number of backlinks, maybe it had many good ones previously and is due to be re-indexed?

Its because the formula Ahrefs use to calculate DR is retarded. They look of the TOTAL number of external links of the website and divide the DR between them. For example:

You have link from BBC, but they have 500k external links, so despite that they have DR 90 you will get 0,01 DR increase.
I get link from shitty PBN with 10 DR, however there are no other external links so I get increase of 5 DR.

Its nonsense, but it is what it is.