  Atmospheric escape plays a fundamental role in shaping the properties of
exoplanets. The metastable near-infrared helium triplet at 1083.3 nm (HeI) is a
powerful proxy of extended and evaporating atmospheres. We used the GIARPS
(GIANO-B+HARPS-N) observing mode of the Telescopio Nazionale Galileo to search
for HeI absorption in the upper atmosphere of five close-in giant planets
hosted by the K and M dwarf stars of our sample, namely WASP-69b, WASP-107b,
HAT-P-11b, GJ436b, and GJ3470b. We focused our analysis on the HeI triplet by
performing high-resolution transmission spectroscopy. When nightly variability
in the HeI absorption signal was identified, we investigated the potential
influence of stellar magnetic activity by searching for variations in the
H$\alpha$. We spectrally resolve the HeI triplet and confirm the published
detections for WASP-69b (3.91$\pm$0.22%, 17.6$\sigma$), WASP-107b
(8.17$^{+0.80}_{-0.76}$%, 10.5$\sigma$), HAT-P-11b (1.36$\pm$0.17%,
8.0$\sigma$), and GJ3470b (1.75$^{+0.39}_{-0.36}$%, 4.7$\sigma$). We do not
find evidence of extra absorption for GJ436b. We observe night-to-night
variations in the HeI absorption signal for WASP-69b, associated with
variability in H$\alpha$, which likely indicates the influence of stellar
activity. Additionally, we find that the HeI signal of GJ3470b originates from
a single transit, thereby corroborating the discrepancies in the existing
literature. An inspection of the H$\alpha$ reveals an absorption signal during
the same transit. By combining our findings with previous analyses of GIANO-B
HeI measurements of planets around K dwarfs, we explore potential trends with
planetary/stellar parameters that are thought to affect the HeI absorption. Our
analysis is unable to identify clear patterns, emphasising the need for further
measurements and the exploration of additional potential parameters that might
influence HeI absorption.
