Songs marked as Downloaded before connected to Wifi - No Re-Download in High quality?

[seltsam23]

Workflow

So, I'm away from home (no Wifi) and discovering new Music on Spotify.

I find a new Album I like and mark it for later "download". My quality settings are set to low on Streaming (Data plan), but Highest for download on Wifi.

What I expect:

Spotify will happily stream the new discovered Album on low quality until I connect to a Wifi. It then will download the album in highest quality as set in the settings.

What actually happens:

Spotify sets the green downloaded-icon for songs listened to on low quality via my data plan already. When afterwards connecting to Wifi it (seems to) only download the songs that were not yet listened to (and thus marked as 'downloaded').

What I seemingly end up with, is a downloaded Album consisting of songs with lowest and highest quality. This is obviously not acceptable.

Questions

1.) Is my assumption correct, that spotify is keeping the low-quality downloads instead of overwriting them with high quality versions after Wifi-Connection?

2) If yes, like...wth? How can pass this quality control?

Device, Version

Samsung Galaxy S7 Edge, Android, Spotify Latest