Generally, it can be considered safe (I use it myself on all of my devices), but security is not a binary thing, so it depends on what do you want to protect it from. For example, if you don't use a primary password or disk encryption, and your device gets stolen, then all your passwords can be compromised. But this is also true if you don't use Lockwise, just the browser's default password store.

So if you have a more precise question, then please elaborate.