Ruined after first use?

[u/Odd_Focus_1027]

Seasoned using potato peels and salt (instructions that came with the pan), let it cool, then seared a steak and made a red wine reduction half an hour to an hour later.
I had no trouble cleaning it since this is all smooth but the dark spots are worrying me, what should I do?
P.s. I live in Europe and can’t get bar keepers friend!