Essentially, If you're a fragging shazbot and decide that utilizing TOR on a machine that isn't yours, on a network you can't control, and break OPsec by utilizing tools that aren't secure you can be compromised.
Nothing new under that old sun.
Barring the usual DNS, Timing Correlation Attacks, and general OPSEC fuarrrkeru that is covered in much better detail by the related vid, they can attack by either using a Traffic Correlation Attack, a Sybil Attack, or through Compromising an Entry Guard (Lab Proven Only).
In any case, these attacks are often resource intensive and either require a high-risk low probability attacker (likely a state actor), a lucky fox hunter, or simply an area virtually devoid of TOR relays.
Mind you I'm not the most well read on the subject and definitely not an authority on this topic, but this is just the information I've gathered in a limited timeframe.
TL;DR TOR itself has some kinks that might compromise some of the information you're sending but provided you follow proper procedure, does not directly compromise user anonymity.
State level actors are a serious threat for this reason as they do not need to find an exploit in TOR to unmask you and have the resources to pursue unlikely or unconventional avenues of attack.