SPA on Nostr: What is that?

{ "id": "fdee41c5707221af892eaa23224759f9b162a1dd9c73ad1af092322c36021732", "pubkey": "4a38463c2a75e68c24416e7720a3b3befbb0ea6872d5a04692c39e18e8f2dcac", "created_at": 1734512968, "kind": 1, "tags": [ [ "e", "2d1f040a35cdf016240e4ed8e0e1713890cdc517a1c483c63383f841a1425cea", "", "root" ], [ "p", "50d94fc2d8580c682b071a542f8b1e31a200b0508bab95a33bef0855df281d63" ] ], "content": "What is that?", "sig": "2210a75cfe040e1fd3a7d4dd667e2f9bfb6f333f79917f1c49729d57435c5c33c95a4aa34768f7155debd67e63e7ec80bc9420a5a5bdc48bfead96880455b00e" }