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We investigate various scenarios which include interaction forms between darkmatter and dark energy that exhibit sign reverse, namely where the transfer ofenergy between the dark fluids changes sign during evolution. We study thelarge-scale inhomogeneities in such interacting scenarios and we confront themwith the latest astronomical data. Our analysis shows that the sign-changeableinteraction models are able to produce stable perturbations. Additionally, thedata seem to slightly favor a non-zero interaction, however, within $1\sigma$confidence level (CL) the scenarios cannot be distinguished fromnon-interacting cosmologies. We find that the best-fit value of the dark-energyequation-of-state parameter lies in the phantom regime, while the quintessenceregion is also allowed nevertheless at more than 2$\sigma$ CL. Examining theeffect of the interaction on the CMB TT and matter power spectra we show thatwhile from the simple spectra it is hard to distinguish the interacting casefrom $\Lambda$CDM scenario, in the residual graphs the interaction is indeedtraceable. Moreover, we find that sign-changeable interaction models canreconcile the $H_0$ tension, however the $\sigma_8$ tension is stillpersisting. Finally, we examine the validity of the laws of thermodynamics andwe show that the generalized second law is always satisfied, while the secondderivative of the total entropy becomes negative at late times which impliesthat the universe tends towards thermodynamic equilibrium.

Observational constraints on sign-changeable interaction models and alleviation of the $H_0$ tension