Boris Gudenuf
Deity
It has been ' thing' in my games, but not to the same extent (this might be because I have been playing Huge maps exclusively since before the last patch, though).AI forward settling hasn't really been a thing since 1.1.1, or whatever the early patch was that hit that specific pain point r.e. AI behaviour.
I haven't noticed it (as a repetitive problem, at least) in quite a while.
The AI will place a settlement just under 10 tiles away from my nearest settlement, and then get angry because I'm too close to him.
I have only seen one instance of absolutely 'in your face' forward settling in a half-dozen games, and that was when we were both on a coastal strip with mountains preventing any expansion except towards each other: the AI put his third settlement so that the boundaries of his settlement coincided with the boundary of my settlement - but he really had nowhere else to go, so that was a map that basically forced an early war.
What I find much more annoying is the AI granting a settlement in a peace deal that is on the far side of his territory from me (or another AI) and completely isolated. I have been able to manipulate these situations in my favor, but the AI seems completely unable to, and so it results in a near-continuous state of animosity between them, frequently to their mutual detriment.
In the Exploration Age I finished last night, for example, 6 AI civs were in two alliances of 3 and 3, and they spent most of the Age at war with each other other, ending the Age in a ridiculous patchwork of isolated settlements isolated from any capital and scattered all over the map. Worse, in the Crisis period not one of those settlements flipped to any of the neighboring Civs despite being underdeveloped and isolated - and in at least 3 cases that I could observe, Unhappy and burning down their own improvements.
My preference would be, an isolated unhappy settlement surrounded by foreign Civ(s) without serious attempts at garrisoning and pacifying it should be nearly certain to flip to another Civ during the Crisis or the X period between Ages. If the Crisis and inter-Age period means anything, that should be a no-brainer, I would think.