Many aspects of your computer end up in browser fingerprinting. So even if you do end up using multiple browsers temporal coupling and secondary signals may let observers make a (low-confidence) link to you.
Tie that all together and it may very well be possible to tie an upload using the Tor network to a particular user visiting some random website at a later date.
You're leaking bits all the time and not all that many of them are required to uniquely identify you.
See https://33bits.org/ for an easy to consume introduction.