Based on the information you provided, I can say that the Ceruledge was not hacked. The trainer who traded you the Ceruledge caught the it in a Tera Raid battle, as Pokemon caught from Tera Raids will say that the original trainer met them in a crystal cavern for their location. To be more specific, the trainer got it from a 5 star raid, as 5 star raid Pokemon are always level 75 when you catch them, and they are guaranteed to have 4 perfect IVs. (31, and the stats with 31 IVs will say Best when you use the judge feature) In other words, the Ceruledge you got is legit, and the trainer who traded it to you probably already had another Ceruledge in their boxes to trade you one they got from a Tera Raid battle.
Sources: This, and experience
