  van Dokkum et al. (arXiv:2309.07969) reported the discovery of JWST-ER1, a
strong lensing object at redshift $z\approx2$, using data from the James Webb
Space Telescope. The lens mass within the Einstein ring is $5.9$ times higher
than the expected stellar mass from a Chabrier initial mass function,
indicating a high dark matter density. In this work, we show that a cold dark
matter halo, influenced by gas-driven adiabatic contraction, can account for
the observed lens mass. We interpret the measurement of JWST-ER1 in the
self-interacting dark matter scenario and show that the cross section per
particle mass $\sigma/m\approx0.1~{\rm cm^2/g}$ is generally favored.
Intriguingly, $\sigma/m\approx0.1~{\rm cm^2/g}$ can also be consistent with the
strong lensing observations of early-type galaxies at redshift $z\approx0.2$,
where adiabatic contraction is not observed overall.
