  The coexistence of superconductivity and ferromagnetism is an intrinsically
interesting research focus in condensed matter physics but the study is limited
by low superconducting ($T_c$) and magnetic ($T_m$) transition temperatures in
related materials. Here, we used a scanning superconducting quantum
interference device to image the in-situ diamagnetic and ferromagnetic
responses of RbEuFe$_4$As$_4$ with high $T_c$ and $T_m$. We observed
significant suppression of superfluid density in vicinity of the magnetic phase
transition, signifying fluctuation-enhanced magnetic scatterings between Eu
spins and Fe 3$d$ conduction electrons. Intriguingly, we observed multiple
ferromagnetic domains which should be absent in an ideal magnetic helical
phase. The formation of these domains demonstrates a weak $c$-axis
ferromagnetic component probably arising from Eu spin-canting effect,
indicative of possible superconductivity-driven domain Meissner and domain
vortex-antivortex phases as revealed in EuFe$_2$(As$_{0.79}$P$_{0.21}$)$_2$.
Our observations highlight RbEuFe$_4$As$_4$ is a unique system which includes
multiple interplay channels between superconductivity and ferromagnetism.
