lme4::lmer reports “fixed-effect model matrix is rank deficient”, do I need a fix and how to?

Question

I am trying to run a mixed-effects model that predicts F2_difference with the rest of the columns as predictors, but I get an error message that says

Answer 1

This response does an excellent job of explaining what rank deficiency is, and what the possible causes may be.

Viz:

1. Too little data: You cannot uniquely estimate n parameters with less than n data points
2. Too many points are replicates.
3. Information in the wrong places.
4. Complicated model (too many variables)
5. Units and scaling
6. Variation in numbers: 12.001 vs. 12.005 & 44566 vs 44555
7. Data precision: Even Double-precision variables have limits