On the degeneracy between $f\sigma_8$ tension and its Gaussian process
  forecasting
  In this Letter we reconstruct the growth and evolution of the cosmic
structure of the Universe using Markov chain Monte Carlo algorithms for
Gaussian processes. We estimate the difference between the reconstructions that
are calculated through a maximization of the kernel hyperparameters and those
that are obtained with a complete exploration of the parameter space. We find
that the difference between these two approaches is of the order of $1\%$-$5\%$
depending on the selected kernel. Furthermore, we compare our results with
those obtained by Planck Collaboration 2018 assuming a $\Lambda$CDM model and
we do not find a statistically significant difference in the redshift range
were the reconstructions of $f\sigma_{8}$ have been made in the literature,
which will impact seriously the reported cosmological tensions.
