Few weeks edit; new pictures attached. I recognise it but plantnet didn’t seem very confident
Coming up in my garden right next to some forest (primarily oak mixed with beech, birch, maple) in southwest Sweden. Last year i dug the area out and removed (most) roots. Not much came up but this little sprout. I suppose it could be roots reaching in from the adjacent forest.
That looks a lot like bamboo.
Dig it out before it takes hold, lest you have a new forest in 2 years.
Theres never been bamboo around here afaik, nor have i brought any plants or soils in from elsewhere.
I really doubt it is bamboo but thanks for the guess!