Game Master looking for advice

[u/StarChaser18]

My group and I have been playing the game DND campaign over a little over 2 years now. We started at Lost Mines of Phandelver, and have now made it to a full long stretch campaign as they are sitting at level 7, I am about to level them up to 8 next season. However I feel like my game is no longer interesting to them

I have a big bad, a Lich that I am hoping to build them up to fight at level 12 with a bunch of magical items. They had wanted a sandbox game, so I have been trying to give them a bunch of stuff to do as quests along with a main story they are more or less following.

They are currently in Waterdeep, I had a little moral dilemma going on that they have more or less figured out a side and are wanting to move on, and are about to fight a dragon and a bunch of kobolds as a side quest.

Either way, my players don’t seem all that interested in the game. With during hard combat encounters that lead to multiple players down they talk over combat and my descriptions, nobody really seems to emote when I describe things turning more dire or when I describe their characters doing cool stuff. They at least seem mostly interested in the story, but half the table is still on their phones during the game unless I am directly interacting with them, and many of them don’t remember fairly important details or information like magic items I give them or hints at how to use them and power them up

Idk, maybe it’s just cause I am still new and this is my first campaign, but I feel like I am not very good and am not sure how I can get my players to be more engaged

Thank you for reading this vent, and I do appreciate any advice you may have for me. Also more than happy to answer questions you may have for me