edwin I am concerned about browser fingerprinting and made a couple of tests with fingerprint.com website.
What you are seeing is their Fingerprint Pro product test. Fingerprint Pro is very comprehensive and it is VERY difficult to combat against their Pro product. I saw this blog post online a while ago and it seems like Tor Browser on a desktop is the only big way to beat their system:
https://www.bitestring.com/posts/2023-03-19-web-fingerprinting-is-worse-than-I-thought.html
edwin I tried to configure Vanadium, but no matter what I am doing (clear the cache, change IP), they still see am I the same person.
You will likely not be able to beat Fingerprint Pro with Vanadium.
See this comment by the GrapheneOS account: https://discuss.grapheneos.org/d/4242-brave-vs-vanadium/10
An adversary with the right resource would be able to tell if you were using GrapheneOS anyhow from other metrics, same post also explains.
edwin Bromite however is performing good if I am using it in incognito mode.
The anti-fingerprinting in that browser is just done by them randomizing all sorts of details, it's not very efficient considering the adversary can just track you based on the details that remain the same and seeing that they change on every page you navigate in a sequence. Randomness also would make you stick out like a sore thumb if a detail they provide would be very unrealistic
Also, it is not recommended by devs and mods because the official repository is very outdated and so is missing security updates. While there are people maintaining updated versions themselves, they don't have any guarantee of being stable. Fingerprint Pro likely would fingerprint this browser by chance just from the randomness alone.
edwin My question is, at what risks am I exposing myself by browsing anonymously ? I use Vanadium for websites that require login or any kind of personal information.
Being seriously anonymous on GrapheneOS would be difficult, and I would suggest use a different setup, but... to answer your question, there wouldn't be any serious risk other than being looked as suspicious, providing you behave properly.
Anonymity is something that cannot exactly be achieved by using a piece of software. It also requires changing behaviours, habits and internet lifestyle. If you are trying to be anonymous you should completely distance yourself from anything unique to you or would stand you out. The Whonix docs has a great list of examples, although these are Tor user centric:
https://www.whonix.org/wiki/Tips_on_Remaining_Anonymous