Bamboo question about Phyllostachys_bambusoides

https://en.m.wikipedia.org/wiki/Phyllostachys_bambusoides

This beautiful huge bamboo is growing on an old garden space.
We have cut some every winter with the owner's permission.

The lot sold last fall and we decided we had enough cane stored in the shed so didn't ask the new owner if we could cut.

The leaves have always been green year round for the past eight years but this winter the leaves have gone from green to yellow to almost a bronze color.

It is just a half block away and 20 feet tall so we have a good view of the leaves...have not walked over though so no pictures.

My question is, are there any natural reasons that it might turn this color?
If we've identified correctly it doesn't seem likely it is flowering.

We won't mention or discuss the unnatural cause I'm concerned about

Sounds as though it's on the edge of it's hardiness zone. A quick search indicates that species is hardy to about 5 - 10 degrees Fahrenheit. (One site seemed to think -5.) Not to worry, though. Bamboo hardiness isn't rated like other plants. It's hardiness temp isn't the temp that kills it, but the temp at which the leaves drop. I bet in the spring it either gets it's leaves back or grows new shoots. (Likely both.)

I hadn't thought about the cold since it's survived through even colder winters here but that may be it.
No below zero temps but some longer stretches in the teens than usual...maybe a week or so? And maybe stressed from that sort of cold several years in a row?

The bamboo has spread and survived there for decades....started as just a bit on the edge of someones garden.

Thanks!