A I have tearing again with Intel graphics, issue is strange because only one screen of two has tearing.
Xpresent or GLX?
I don't know, default.
Which driver, intel or modesetting?
Rather intel driver.
Have you tried with the modesetting driver instead? (this is default, the intel driver hasn't got any release in years, 2.99.997 was tagged 5 years ago).
xfwm4 relies on either GLX or Xpresent to swap buffers on vsync, if you get tearing, there is not so much it can do.
That said, this could be simply that the two outputs have completely different refresh rates and the driver cannot sync on both simultaneously, you could try changing the refresh rates of your monitors to be closer to see if that makes any difference.
In any case, it works for me, tear free in multi monitor setup on intel (using the modesetting driver), with both Xpresent (with https://gitlab.freedesktop.org/xorg/xserver/commit/6e199e46) and GLX, tested on a few laptops.
I'm not sure which driver I have, but this tearing is something new, I observed it about 1 or 2 weeks ago, before was ok.
Could be https://gitlab.freedesktop.org/xorg/xserver/issues/839
Graphics: Device-1: Intel Xeon E3-1200 v2/3rd Gen Core processor Graphics driver: i915 v: kernel
Display: x11 server: X.Org 1.20.5 driver: intel unloaded: modesetting resolution: 1920x1200~60Hz, 1920x1200~60Hz
OpenGL: renderer: Mesa DRI Intel Ivybridge Desktop v: 4.2 Mesa 19.0.6
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