衰える example sentence question

[Ethanol10]

Hi, I was wondering if anyone could explain what 霜が降っていること means? The example translation suggests something like “marbled”, but I have no idea where I can read up about it?

Here is the full sentence, in the event that I’ve screwed up my understanding:

「数年前にこの牛肉を食べた時は、非常に良く熟成されて霜が降っていることに感動したんですが、今はちょっと味が衰えたみたいでとても残念ですね。」

“When I had this beef several years ago I was really impressed by how well it was aged and marbled, but the taste seems to have declined a bit and I’m really disappointed.”

[Janime6]

霜降り can specifically mean marbled meat, so you just turn that into 霜が降っている, I’d assume.

霜降り:
脂肪が網の目のように入っている牛肉。

[Leebo]

I found people saying that 霜が降る and 霜が降りる can be used to talk about beef marbling.

For the actual weather phenomenon of frost on the ground, it appears that 霜が降りる is more common.

And 霜降り is not used to talk about frost, only meat or cooking, haha.

[Ethanol10]

Ah I see, that makes sense, thank you!