I wanna make more of myaccounts in the internet secure with two factor. I don’t know much about it, but found out about Fido 2 and so. The security key my webbrowser shows often is the one from Yubico (BTW, I would like to get one that works with Linux, with USB and for phone with NFC) I got concerned when I noticed that Yubico is from USA, (??) Because I think NSA and thibgs like five eyes and so. Is there actually a risk that the for example is made an backdoor in the key?
That depends on your threat model. For most people, the attack is probably unlikely to affect them, but I would recommend reading about the flaw yourself. It’s not hard to understand.
Also, this was not the fault of Yubico but a supplier, and instead of waiting for the supplier, Yubico patched the flaw themselves by providing a custom library.
Whether you should replace your current Yubikey 5 is up to you.