If they became best friends on the job that's one thing (but a long term problem)
If they became friends before and then hired each other it's a red flag
Cronyism is the practice of partiality in awarding jobs
and other advantages to friends or trusted colleagues,
especially in politics and between politicians and
supportive organizations. For instance, this includes
appointing "cronies" to positions of authority,
regardless of their qualifications.
If they became friends before and then hired each other it's a red flag
https://en.wikipedia.org/wiki/Cronyism( essentially a variation of https://en.wikipedia.org/wiki/Nepotism )