I can confirm that. At my X3 Pro it sometimes even starts if I have 10 apps open that constantly use the background sync service. But I also had that on aOS 12 on my other device.
Nah, I don't experience any problems with Spotify and Poweramp.
/* * We are not responsible for bricked devices, dead SD cards, * thermonuclear war, or you getting fired because the alarm app failed. Please * do some research if you have any concerns about features included in this ROM * before flashing it! YOU are choosing to make these modifications, and if * you point the finger at us for messing up your device, We will laugh at you. * It is your fault because you chose to do all the modifications on your device. * Remember projects like these and the work done on them is a hobby to the * contributors and the team members, no one is working for you nor is getting paid for it * have some respect for the work done by them since it is done purely on interest or a hobby */
It's a free hobby.