Tiktok probably generated a unique link to the video just for you when you shared it so that whomever the recipient is will know that you shared it. And then your friend opened said link and tiktok connected the dots and linked the accounts in a DM with the video. Pretty easy for them to do on their end, and they probably see it as a convenient feature to users.
Also, lost fedditors
And if not teaching in the traditional academic/classroom setting, at least spread awareness about why privacy is important, why one should care, and what can be done to protect one’s privacy to friends/family/others who will listen
Glad you’re okay. The vibration while braking might be your wheel is out of true, or damaged brakes, or something else. And the shifting could be as simple as a bent derailleur hanger, pretty easy fix! Hard to tell without seeing it. Definitely have the bike looked over by a mechanic, you might just need a few minor repairs and can keep riding it. New helmet 100% though!
Stallman