Weizhe Liu is a postdoctoral scholar at Steward Observatory, University of Arizona. He is mainly interested in AGN host galaxies and feedback in different systems across cosmic time, with a current focus on high-z quasars and nearby dwarf AGN. He received his PhD from the University of Maryland in 2022. Before that, he obtained his master’s degree from Shanghai Astronomical Observatory in 2016 and his bachelor’s degree from Nanjing University in 2013.AGN feedback through powerful outflows is deemed a critical component in modern galaxy evolution models, which may regulate supermassive black hole (SMBH) accretion, quench star formation, and shape the circumgalactic medium (CGM). However, the properties and impact of such feedback, particularly within the first billion years after the Big Bang, remain poorly known. In this talk, I will describe our on-going efforts to address this open issue. To begin with, I will present our recent discoveries of fast, galaxy-scale outflows in the earliest quasars at z > 5, with the most distant one at z ~ 7.5 as revealed by the JWST integral field unit (IFU). Based on our study of quasar outflows at z~5-6 through a JWST IFS survey program, we find that extremely fast (with velocities reaching 8400 km/s), galaxy-scale outflows are more prevalent at z > 5 than at later cosmic epochs, with some of them among the most rapid outflows known in the universe so far. These outflows may easily escape their host galaxies and impact the CGM. They may be powerful enough to provide significant feedback to their host galaxies and lead to the quenching of the earliest massive galaxies. Next, I will report some more direct evidence on the quasar feedback-induced quenching in such early quasar host galaxies. With the JWST IFU data on one of the earliest quasars with a quenching host galaxy at z ~ 6, we have discovered a galaxy-scale outflow with a mass outflow rate exceeding the current star formation rate of the galaxy, which is able to quench and/or significantly suppress the star formation within the system. At ~900 Myrs after the Big Bang, this quasar host galaxy already lies on the local M-sigma relation, and will likely evolve into quiescent/post-starburst galaxies at lower redshifts given their similar physical properties. Quasar feedback via outflows likely helps with these processes significantly. Moreover, molecular gas is the direct fuel for star formation, and molecular gas outflows should thus regulate the star formation activities more profoundly. Our preliminary results suggest that such molecular gas outflows already exist as early as z ~ 7.5. Finally, in addition to quenching, such quasar outflows could also shape the CGM. Our preliminary results suggest that strong outflows could indeed shape the CGM traced by Lyman-alpha nebulae. Overall, our studies indicate that quasar feedback plays a critical role in the evolution of the first generation of SMBHs and massive galaxies in the universe.