In the last few months I've had 4 numbers added at the end of my YouTube user ID. I didn't do this, they just appeared a few months back.I might be being too paranoid, but I've noticed that when you share a YT video that it appends an ID to the URL, I suspect that this is so that the source of videos on social media can be traced, and I have concerns about this.
For example, you get something like this below added on to the end of the video URL, you can delete this part (everything from the ? onwards) and the video link will still work
?si=YMt5W8TWATfu66FU
Look at any YouTube comments section & you'll see that some folk have the 4 numbers & some don't. Do you have any idea why this is?