Same crap here. My new and pricey iPhone X (256 GB, iOS 12.0.1) is rendered utterly useless for music playback, and I'm so incredibly angry and frustrated - listening to music is 80% of my phone usage, but I can't listen to anything in iTunes without it randomly pausing, skipping around, jumping to the next song, pulling up Siri, fast-forwarding through tracks at hyper-speed, and skittering its way through songs every. single. time. I try - which is every single day, at least four times a day, for around an hour or so at a pop while I'm commuting and getting around the city. It's beyond maddening. I've been pouring through the internet for nearly a month now trying to find answers and testing solutions, and have seen the blame laid on bad headphones (I'm using a brand new $250 pair of Bose noise-cancelling earbuds, but it does this on my old pair, as well as with two other pairs of headphones I tried, none of which ever produced this problem until one of these latest OS updates), on the headphone's mic controls being faulty (again, I tried several different pairs to no avail) a bad lightning-to-headphone-jack dongle (swapping THAT out made zero difference), having "Raise to Wake" activated (no difference when turned on or off), having Siri activated (no difference here either) dust in the lightning port (again, no difference), turning off Bluetooth, turning ON Bluetooth... all followed by hordes of people writing in to say that nothing being suggested as a fix made any difference, and with seemingly no one being able to isolate what's causing the problem because they were experiencing it on many different phones, running many different OS updates, using headphones or not, etc. I also saw different apps being blamed: most notably any music playback or streaming apps like Spotify, and people being told to delete and reinstall, which was equally worthless. People were also told to and tried factory-resetting phones and re-downloading their entire enormous music libraries for hours on end without it making a single dent in the problem.
Whatever is going on here, it's squarely on Apple, and they need to figure it out and fix it FAST. It's absolutely infuriating to have no answers or solutions when you pay this much for a product.