Music libraries do not match up (Mac & iPhone 16 pro)

I think I have two different issues going on here, but both are related to my music library.

Over the years, I have purchased hundreds of tunes on the iTunes app. Almost all the purchased music on my new iPhone 16 Pro is grayed out. (This must have occurred when I bought my iPhone 16 Pro this past earlier this week because I listened to my Hamilton soundtrack last week--it's now grayed out too.)

Then I went to my laptop where I noticed that some of the tunes/albums I've bought from the iTunes library over the years are showing on my phone (grayed out), but aren't even listed in the Music library on my Mac laptop. I had a subscription to Apple Tunes for about 3 months (for the "3 months free" promotion).

I spoke with three different Apple customer service folks on Wednesday night who were unable to help me. Supposedly, I should receive a phone call from a tech person within 5 days (from Wednesday's phone call).

I am super frustrated!

[Re-Titled by Moderator]