I only have pics of leaves now. When it blooms it has flowers similar to an asilbe. The roots run underground and the plant pops up everywhere. The garden centre I got it from said it was an astilbe; but, I’m reading that astilbe are not invasive. (?)
Your plant looks like false spirea(Sorbaria sorbifolia), an invasive shrub that spreads by suckers. The Missouri Botanical Garden has a helpful summary of this plant’s characteristics. See also the Ontario Invasive Plants Council’s Beautiful non-invasive plants for your garden, which provides additional information about your garden thug, as well as alternative (non-invasive) shrubs that may interest you!
False spirea is lovely in areas where you want it to grow, but to get rid of it, see an earlier post on the Toronto Master Gardeners website, False spirea. If you decide to leave the bush in place but want to control its spread, prune it hard in the early spring, just before the buds start to come out (as it blooms on new growth) and watch for (then dig out) those suckers!
You may want to return to your garden centre to tell them that the “astilbe” (a lovely, quite delicate looking, non-invasive perennial) turned out to be something quite different.