Sorry for you.
Which mods do you have installed?
SU? Which? Original, Systemless or Magisk?
Xposed? Which Version? Developer?
At first delete all backups in TWRP/backups (internal and external) or backup them to a harddisk/PC. Try to take a new backup, if it fails, go in TWRP to Advance and "Copy log", it will be copied to external sd card under twrp/recovery.log or twrp/backups/recovery.log, post it. Maybe something is wrong with you system/data files.
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Had to restore a system backup, all went good, only restored "system".