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in my case it's solved
Indeed, they fixed it. But they didn't even care to come here and tell us it was fixed. Thanks for the support, Spotify! All good, people.
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To fix it, you follow step 1 for Debian at https://www.spotify.com/nl/download/linux/, that is
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 931FF8E79F0876134EDDBDCCA87FF9DF48BF1C90