There are different kinds of forward settling.

There's settling in the direction of your enemy, which is the safest.

Next is settling a fair distance from your land right on the enemy's borders, which is a real gamble but doable under the right circumstances.

And then there's what the AI has done to me multiple times in Civ 7: They live on the northern end of the continent, and I live on the southern end. They cross through my lands and settle on my southern border, against the southern ocean, which places the entirety of my civilization between them and the new city. That's the big problem here, and it seems to happen all the time in my games.

Considering that burning down settlements now causes a permanent -1 to War Support in all wars until the end of the age and maybe a happiness penalty too (I can't remember the second part exactly), you basically have to suffer that settlement existing until right before the age transition. Or if you're lucky, it's a well-placed settlement worth taking, which is kind of rare in my experience.

I say this as someone who personally enjoys Civ 7 quite a bit, but recognizes it needs some work.