Seeking HR Perspective: Hiring Challenges with a 3-Month Notice Period

I’m a C++ developer with 4 years of experience and currently trying to switch jobs. I have a 3-month notice period. Even when L1 interviews go well—and in one case after clearing 3 technical rounds—I’m not getting shortlisted for the HR round or receiving callbacks. Since it’s already December, I wanted to understand from HRs: is the notice period the primary reason, and realistically, when does the market usually open up for candidates with a 3-month notice period?