Transferred Data To New Phone but ...

I transferred my data last night from my iPhone 14 Pro Max to my new 16 Pro Max. I backed it up on iTunes afterwards and all of the music I uploaded myself from old CDs was not there after that.

I am now trying to get it to move over via iTunes and it keeps telling me that some of the items in the iTunes library were not copied to the iPhone because they could not be found. Does this mean I have to go back an manually add all of these songs again and the cover art?

How do I keep this from happening every time I sync my phone. It has done this for YEARS until I just stopped adding my old music from CDs to my iTunes and use YouTube Music to play music in my car but I'm feeling nostalgic and want to listen to these particular albums now.

Thanks y'all! It's 2024 and I would think I could have airdropped my albums but now they are totally gone from my other phone too.