Dark energy is a constant in the standard model (equivalent to the cosmological constant) and all observations I'm aware of besides the Hubble tension are consi

Dark energy is a constant in the standard model (equivalent to the cosmological constant) and all observations I'm aware of besides the Hubble tension are consistent with it being constant. But nothing stops you from going beyond the standard model, and people have done that and proposed models with a dynamic dark energy density, for example quintessence models. They'd solve some theoretical issues with the standard model, but so far no observations have been precise enough to differentiate between those models and the standard model. Having a dynamic dark energy is a proposed solution to the Hubble tension: https://arxiv.org/abs/2103.01183 https://arxiv.org/abs/2103.01183 That is, besides a whole family of potential other solutions: Dark energy in extended parameter spaces [289] Early Dark Energy [235] Early Dark Energy [229] Dynamical Dark Energy [309] Phantom Dark Energy [11] Decaying Warm DM [474] Metastable Dark Energy [314] Dynamical Dark Energy [11, 281, 309] Neutrino-DM Interaction [506] PEDE [392, 394] GEDE [397] Interacting dark radiation [517] Elaborated Vacuum Metamorphosis [400–402] Vacuum Metamorphosis [402] Self-Interacting Neutrinos [700, 701] IDE [314, 636, 637, 639, 652, 657, 661–663] IDE [314, 653, 656, 661, 663, 670] IDE [656] Self-interacting sterile neutrinos [711] Critically Emergent Dark Energy [997] Unified Cosmologies [747] Generalized Chaplygin gas model [744] f (T ) gravity [814] Scalar-tensor gravity [856] Galileon gravity [876, 882] ¨Uber-gravity [59] Modified recombination [986] Power Law Inflation [966] Reconstructed PPS [978] Super ΛCDM [1007] f (T ) [818] Coupled Dark Energy [650]