Browning leaves issue

Hello Guys! Can anybody tell what is the cause of this? 3 weeks old plant, grown in Soil/perlite/. From researching online it may look like potassium deficiency but im not too sure2DF690D5-5E97-49C3-B6BF-B60A1597DBD5.jpeg2DF690D5-5E97-49C3-B6BF-B60A1597DBD5.jpeg2DF690D5-5E97-49C3-B6BF-B60A1597DBD5.jpeg4B331BDE-B8AE-42A8-87F5-10CDD0AD130B.jpeg
 
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