Meta Sr. Software Engineer interview questions

Faced phone interview, solve 2 problems in 40 mins and got selected for on site. Later on site I had to face 5 more interview. The interview was interesting, as i was not prepared well I did not get an offer.

The interview consisted of a Phone screen followed by a virtual on-site (four interviews). Questions were fairly straight forward (LC medium). System design question threw me off, it wasn't the typical "design an app" question. It can be fairly open ended, so prepare for anything.