I synced desktop brave with mobile brave and I only see bookmarks from desktop . I don’t see history from my desktop brave in My android Brave.
Sync currently only syncs TypedURLs, it is what it is because Chromium made it that way and for years it has been like that.
Recently Chromium made a flag available to sync history and Brave is working in that to allow users to sync all history like the name says. so it is a WIP https://github.com/brave/brave-core/pull/16705 and you can follow the progress there.
It is just a Draft so, it is not even ready to be reviewed, and then it will take months to hit Stable.
But for example, Sync has received some changes, like, recently Brave Nightly added the button to delete Sync Chains, so they are working to improve things. The only thing is that usually it takes couple months to hit from Nightly to Stable when merged.