With respect, unless you provide irrefutable proof that the router cfe has been compromised then no-one is likely to help, at the very least if you have a concern, then contact Asus & the r-merlin dev and go from there.....
latest firmware for XT8, https://github.com/gnuton/asuswrt-merlin.ng/releases/download/3004.388.9_2-gnuton2/RT-AX95Q_3004_388.9_2-gnuton2_puresqubi.w
would be the file to use, you do not have to backup nor reset, prior to flashing a new firmware, I wouldn't recommend restoring a backup from...
Probably because your mixing be wifi with ax wifi, and Asus are still working out the kinks with be class routers, any possibility of moving to ethernet backhaul ?