Can anyone tell me if this plant is a weed?
On this site, we typically use the following definition:
Plant growing in a spot where the gardener doesn’t want it to.
Usually got there on its own.
Some plants have a tendency to spread rather quickly and often they get classified as weeds - because they take over the space intended for other plants. In my garden for example, forget-me-nots are on a mission of taking over the grounds, so I pull them up where I don’t want them and enjoy the unexpected blooms in others. All a question of preferences and gardening goals. Almost philosophical.
So it’s up to you to decide whether the plant in question is a weed to you or not, then act accordingly.
If you want an id, I recommend you check out the tag help for identification and post a new question.