Hey all! I had the same experience - here's what I did to re-download the songs:
First I figured out which songs I had deleted by noticing certain albums were missing tracks. I also tried to think about which playlists I edit a lot and what would be on them...
To re-download them, I had to search for the songs individually in the ITunes Store app on my phone. Once they showed up in search , I clicked the little price and authorized payment. Then I got a "you already bought this, click here to download again" message and downloaded from there!
Note that I could NOT re-download them from my purchases list or from finding the whole album in the ITunes Store! Only via searching for individual songs in the ITunes Store 😵💫😵💫 definitely some BS.
Anyways I hope this helps!