Sappho Bergk 30, not present (AFAICT from searching) in Campbell or Edmonds, is from Athenaeus's Deipnosophistae, book XIII. Here is the text with some of Athenaeus's words around it, as reported by Greek Wikisource:
καὶ τὴν Σαπφὼ δὲ πρὸς αὐτὸν ταῦτά φησιν εἰπεῖν
κεῖνον, ὦ χρυσόθρονε Μοῦσ᾽, ἔνισπες
ὕμνον, ἐκ τᾶς καλλιγύναικος ἐσθλᾶς
Τήιος χώρας ὃν ἄειδε τερπνῶς
ὅτι δὲ οὔκ ἐστι Σαπφοῦς τοῦτο τὸ ᾆσμα παντί που δῆλον.
The last sentence reads «That this poem is not by Sappho is clear to all, I suppose». Why does Athenaeus say that? And why does Bergk have it in his edition of Sappho if Athenaeus says, with reason, that it is not Sappho?
As pointed out by AlexB, Cambpell has it in the "life of Sappho" section, on p. 10 (original) and p. 11 (translation). I hadn't looked there, but only through Sappho's poems, and then after posting I looked through the uncertain authorship fragments section and through the Alcaeus poems section, in vain, of course. Edmonds doesn't seem to have it. It is known as
Fragmentum adespotum 953 PMG.