[fisherman]

The experiments showing gravitational variations are not controlled - https://wiki.tfes.org/Weight_Variation_by_Latitude

Apparently the NIST experiment referencing gravitational time dilation was sufficiently controlled for you.  It demonstrates gravitational variations.

No. There is a reason for why Einstein and physicists have the upwardly accelerating elevator and rocket analogies. It's because experimental evidence shows that gravity behaves as if the Earth were accelerating upwards. These experiments are why Newton's theory of objects falling down through space to the earth was rejected. Gravity operates as if the Earth is accelerating upwards, and this is reflected in the equivalence principle experiments

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As has been pointed out to you numerous times, and you keep ignoring...this only applies locally.  More importantly, it only applies to objects that are in free fall.  Gravity effects countless things that have nothing to do with free fall...from circulatory systems, the way plants grow to roller coasters.

[Longtitube]

What, or who accounts for, and changes the colour of literally thousands/millions of small spots of light, just to make it look like they are redshifted or blueshifted relative to Earth?  What purpose would that serve in a flat Earth model?

Whoah, tiger. Redshift doesn’t change the colour of the stars as we see them: Betelgeuse isn’t reddish because of redshift, nor is Sirius blueish because of blueshift. You’re not alone, I’ve seen others here make the same mistake, but redshift or blueshift in astronomy is the absorption spectra of eg helium within starlight shifting from their regular positions towards the red or blue end of visible light due to Doppler effect. That Wikipedia article you linked explains it.

[RhesusVX]

Whoah, tiger. Redshift doesn’t change the colour of the stars as we see them: Betelgeuse isn’t reddish because of redshift, nor is Sirius blueish because of blueshift. You’re not alone, I’ve seen others here make the same mistake, but redshift or blueshift in astronomy is the absorption spectra of eg helium within starlight shifting from their regular positions towards the red or blue end of visible light due to Doppler effect. That Wikipedia article you linked explains it.

OK, I like your style, and yes, you’re right it’s not a humanly detectable change in colour per se, it’s a shift towards the red or blue end of the spectrum relative to where it would be expected if it were not moving with respect to us. 

https://lco.global/spacebook/light/redshift/

What I’m not clear on is how FET accounts for this observation.  All I seem to find are articles that claim redshift is caused by other things, not just relative motion/velocity, so astronomical doppler effect is ruled out.  We know that expanding space would cause the same effect, and we know that strong gravitational fields can also cause the effect.  So which is it?