Google may have updated the algorithm, which fights against the substandard links. This information was reported by Search Engine Land with reference to multiple reports from foreign webmasters.
American optimizers called this update "Fred". This is how Google employee, Gary Illyes jokingly suggested to call all such updates of the search algorithm.
According to industry experts, the websites with a lot of poor-quality URLs in referenced profiles got penalized.
When asked to comment the new algorithm, the search representatives, Gary Illyes and John Mueller answered that Google is constantly updating its algorithms.
It should be recalled that webmasters noticed a major update of Google's algorithms aimed to fight against referral spamming in February.