Where is rootfs and rootfs_data? (Netgear R6220)

Hello, I've been using OpenWrt for some time, but I am rather new to it. I wanted to extend the storage by adding a usb stick/hdd drive. I followed the extroot configuration guide but I do not have the rootfs and rootfs_data partitions... why is that so?

root@router:~# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00100000 00020000 "u-boot"
mtd1: 00100000 00020000 "SC PID"
mtd2: 00400000 00020000 "kernel"
mtd3: 01c00000 00020000 "ubi"
mtd4: 00100000 00020000 "factory"
mtd5: 03c00000 00020000 "reserved"
root@router:~# cat /etc/mtab
/dev/root /rom squashfs ro,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,noatime 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,noatime 0 0
tmpfs /tmp tmpfs rw,nosuid,nodev,noatime 0 0
/dev/ubi0_1 /overlay ubifs rw,noatime,ubi=0,vol=1 0 0
overlayfs:/overlay / overlay rw,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work 0 0
tmpfs /dev tmpfs rw,nosuid,relatime,size=512k,mode=755 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,mode=600,ptmxmode=000 0 0
debugfs /sys/kernel/debug debugfs rw,noatime 0 0

I'm on 19.07.7 @ Netgear R6220

try ubinfo -a

Thank you for the command, it gave me:

root@router:~# ubinfo -a
UBI version:                    1
Count of UBI devices:           1
UBI control device major/minor: 10:59
Present UBI devices:            ubi0

Volumes count:                           2
Logical eraseblock size:                 126976 bytes, 124.0 KiB
Total amount of logical eraseblocks:     224 (28442624 bytes, 27.1 MiB)
Amount of available logical eraseblocks: 0 (0 bytes)
Maximum count of volumes                 128
Count of bad physical eraseblocks:       0
Count of reserved physical eraseblocks:  20
Current maximum erase counter value:     11
Minimum input/output unit size:          2048 bytes
Character device major/minor:            251:0
Present volumes:                         0, 1

Volume ID:   0 (on ubi0)
Type:        dynamic
Alignment:   1
Size:        21 LEBs (2666496 bytes, 2.5 MiB)
State:       OK
Name:        rootfs
Character device major/minor: 251:1
Volume ID:   1 (on ubi0)
Type:        dynamic
Alignment:   1
Size:        179 LEBs (22728704 bytes, 21.6 MiB)
State:       OK
Name:        rootfs_data
Character device major/minor: 251:2

Is that right that now the rootfs and rootfs_data are both on partition mtd3, via two ubi volumes?

Yes, it is.