IMO it's better to have an internal zoom rather than telescopic. The former eventually introduces dust no matter how much you baby your lens. Kudos to Sony for making this zoom have very minor focus breathing, much less than the RF counterpart and with the optical quality of the new Nikkor 70-200 f2.8!
I've never had an issue with multiple externally extending lenses. But, I guess it depends on how much dust we're talking about. I recall people referring to the EF 100-400mm f/4.5-5.6 as an 'air pump', and being actually disconcerting to use. Yet it was also meant to be an exceptionally good lens through-out the range.
In practice a bit of dust won’t make any difference to image quality, although it may affect resale value. Theoretically, extending lenses allow greater ingress of dust or moisture, but there seems to be no hard evidence that this is the case.
My experience is that focusing and zooming are smoother in non-extending lenses. With extending lenses the centre of gravity shifts as the lens extends - not a problem with a 70-200mm, but with a larger lens such as a Sigma 150-600mm it can be, if the lens is on a gimbal.
Another minor issue is that when an extending zoom is at or near maximum focal length, there can be a small degree of play or wobble, which can be disconcerting although it doesn’t seem to affect sharpness.
The compactness of extending lenses is advantageous when packing gear for travelling, but when in the field I usually work with just one or two lenses, so for me it’s not a factor.
I have a variety of extending and non-extending lenses, and I much prefer the non-extending designs, if all other aspects are equal (sharpness, weight, MFD, bokeh etc).