You are right of course Nox - nothing is 100%.
The triangular
head plate matches the Vyškov Germanic
type - though not the rectangular
part.
Still trying to track down that.
The Vyškov, and the related but kurbschnitt-decorated Prša-Levice
type, date circa the late 5th century.
This particular
fibula comes from eastern Slavonia which at that time was on the borders of the Ostrogothic Kingdom and the Gepidic "Kingdom".
The item is certainly eastern Germanic.
SC