Has not dropped its leaves over the winter in Victoria
The only thing that I could really think of would be a mild winter. If your area is growing quite a bit in size, then the influx of people and building may warm temperature over time in your microclimate. It isn't going to harm the shrub, though.
This page will contain articles that may help you with the care of your shrub:
https://www.gardeningknowhow.com/search?searchTerm=%22hibiscus%22
I'm attempting to propagate hibiscus, and I think I made a mistake initially in that I put an opaque bag over the pot. Today, I replaced that with a clear bag (I feel kinda "duh") -- photo attached. I see they're budding despite my bad, but I'm wondering if I need to keep the bag on it at this point? It's been about 3 weeks since I put them in the dirt, and I read somewhere to keep the bag on for 8 weeks? What kind of light should I keep the pot in? Would just appreciate a little guidance at this point... looking things up online is so confusing! Thanks!
The fact that the stems have leaves means they have roots, so you don't need the bag anymore. Give it as much light as you can, a south or west window is best. They like humidity so you can put the container on a tray of pebbles and keep water in it. The pot should not rest below the pebbles or it will absorb the water and may get root rot.
Here is more:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-container-care.htm
Here is info about a pebble tray (but ignore the photo; it is not a pebble tray).
https://www.gardeningknowhow.com/houseplants/hpgen/what-is-a-pebble-tray.htm
There are nine pages of hardy hibiscus and most of the featured flowers are stated to be for growing zones 4-9. They look like tropical plants to me and I would like to know what the experts think. Is anyone familiar with this site?
We don't make vendor or product recommendations but I would be skeptical here. I have never seen tropical or hardy hibiscus in these color combinations. When I search for multicolor hibiscus online, no reputable company comes up, only individuals selling "rare" flowers on Amazon, eBay or Etsy.
Plus, they have the caution to read the description carefully before ordering. If you want to try it, I suggest only ordering one or two and see if you get what you ordered. The thing is you won't know for several months.
Even though these say they are perennial, I don't believe they are hardy hibiscus. Tropical hibiscus are "perennial" in zone 10.
I have a huge hibiscus Bush in front of a window! I've taken it down by one third each year and then it quickly regrows. I need to take it down to about 3 ft. Will this kill it? It's about 7 ft tall.
Rejuvenation pruning should not kill it. Wait till spring to prune, though. Here is more: