A number of factors are at work:
1. Vapes, Zyns, etc. creating new nicotine addictions in 13-20 year-olds. It's an epidemic in high schools and colleges right now. Once you're addicted to nicotine, trying cigarettes is only a matter of time.
2. Media depictions, always been an issue but recently a number of popular shows (i.e. Peaky Blinders), movies (i.e. Oppenheimer), and artists (i.e. Lana Del Rey) have depicted smoking in a positive light, which has a big impact on young people.
3. Smoking weed, they are weak substitutes for each other and the normalization of smoking weed also means smoking of any kind (including cigarettes) is normalized, and cigarettes are far more accessible.
4. Poor economic conditions always see an uptick in drug use across the board, with alcohol and cigarettes being the primary drivers. It may seem counterintuitive, because those things are expensive, but they're cheaper than vacations, expensive hobbies, or a night out and they provide release and comfort (things that everyone needs to stay sane). Once again, the current economic conditions are hardest on young people, because they haven't had a chance to build up capital (which is doing great, it's labor that is struggling).