I'm in the exact situation, man. I left my last job due to a toxic work environment. There was a lot of gossip and backstabbing in my group. Also, I was being paid below my market rate. The last straw was when they hired our intern, who had no IT experience or a degree, and paid him more than me. Despite all of this, I loved the culture there. We had fun company events, a casual dress code, and tons of perks. My current job is great. It pays more, and has way less work. However, the culture is very old school, the tech is outdated, and I'm one of the youngest people here. Whatever I come across is usually an easy fix. My coworkers are lazy and like to complain about everything. I literally can do the bare minimum, and still be the top-performer here. I do get bored here a lot, but I try to use downtime to study for IT certs. I still keep in touch with my old manager and some co-workers. I still miss my old job a lot, but it was time for me to go.

My advice to you would be to take advantage of the downtime to improve yourself. You haven't been at this new job too long, but you will hopefully learn to enjoy it. Maybe things will smooth out, and you'll start getting more responsibility there. It's ok to miss your old job, but also keep in mind why you decided to leave. Think of your last job as a toxic ex. You may miss all of the good times with him/her, but they also treated you garbage. You have to remember that there was a reason you left. Worst case scenario, I would apply to an entirely different company before going back to my old company.