na-adjective, noun
vexatious; troublesome; complicated
Describes a situation, procedure, or matter that is annoyingly complicated, full of petty details, or causes irritation due to its complexity. Somewhat formal and literary.
この申請手続きは煩瑣で、何度も書類を書き直させられた。
This application procedure is vexatiously complicated, and I was made to rewrite the documents many times.
煩瑣な規則に縛られて、仕事がなかなか進まない。
Bound by troublesome rules, the work just won't move forward.
Standard kanji spelling; both characters are relatively rare, but this is the established form.
Compound of 煩 (annoyance, trouble) and 瑣 (trivial, petty). The combination suggests trouble arising from petty or overly detailed matters.