Meta Onsite E4/E5 Seattle reject

Reached out in Jan.

Feb early Phone
Phone interview 45 mins
Questions: 1. Lexicographic number 2. Dont remember

Onsite

1. Coding - 3 questions. 1. String sliding window, 2. Hard string sliding window extension to first. 3. Binary search of range - Did well in all 3
2. Coding - 1. Paranthesis medium problem. 2. String pattern problem. Match pattern etc.,- Did well in all 2
3. System design - cloud sharing - I should have thought carefully and answered here but was able to complete fine. Not satisfied.
4. System design - feed - interviewer was sick and had to repeat and was not sure if interviewer was even listenting, and delayed completing and could not complete this one. Asked several times which part are they interested in.
5. Behavioral. - standard questions

Got feedback in 3 business days as a reject based on few signals. not sure what signals.

update :ispoke to recruiter she mentioned my system design was not good. should have deep dived. I'm completely baffled. anyway,