  Super-metal-rich (SMR) stars, currently in the solar neighbourhood, are
expected to originate only in the inner Galaxy and have definitely migrated. We
aim at studying a large sample of SMR stars to provide constraints on the epoch
of the bar formation and its impact on the MW disc stellar populations. We
investigate a sample of 169,701 MSTO and SGB stars with 6D phase space
information and high-quality stellar parameters coming from the hybrid-CNN
analysis of the Gaia-DR3 RVS stars. We compute distances and ages using the
StarHorse code with a mean precision of 1% and 11%, respectively. From these,
11,848 stars have metallicity ([Fe/H]) above 0.15 dex. We report a metallicity
dependence of spatial distribution of stellar orbits shown by the bimodal
distribution in the guiding radius at 6.9 and 7.9 kpc, first appearing at
[Fe/H]~0.1 dex, becoming very pronounced at larger [Fe/H]. In addition, we've
observed a trend where the most metal-rich stars, with [Fe/H]~0.4 dex, are
predominantly old (9-12 Gyrs) but show a gradual decline in [Fe/H] with age,
reaching around 0.25 dex at about 4 Gyrs ago, followed by a sharp drop around 3
Gyrs ago. Furthermore, our full dataset reveals a clear peak in the
age-metallicity relationship during the same period, indicating a SF burst
around 3-4 Gyrs ago with slightly sub-solar [Fe/H] and enhanced [$\alpha$/Fe].
We show the SMR stars are good tracers of the bar activity. We interpret the
steep decrease in number of SMR stars at around 3 Gyr as the end of the bar
formation epoch. In this scenario, the peak of bar activity also coincides with
a peak in the SF activity in the disc. Although the SF burst around 3 Gyr ago
has been reported previously, its origin was unclear. Here, we suggest the SF
burst to have been triggered by the high bar activity, 3-4 Gyr ago. According
to these results and interpretation, the MW bar could be young.
