Okay, dvb_create_media_graph is defined in dev-core: Linux source code: drivers/media/dvb-core/dvbdev.c (v5.2) - Bootlin
lsmod | grep dvb has no output, so dvb-core is not loaded which must cause the problem with dvb-usb.
But when I do modprobe dvb-core I get no output, but it still isn't loaded.
Code
$ modprobe --show-depends dvb-usb
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/rc/rc-core.ko
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/media.ko
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/v4l2-core/videodev.ko
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/common/videobuf2/videobuf2-common.ko
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/common/videobuf2/videobuf2-memops.ko
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/common/videobuf2/videobuf2-vmalloc.ko
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/dvb-core/dvb-core.ko
insmod /lib/modules/5.1.16-1-MANJARO-ARM/kernel/drivers/media/usb/dvb-usb/dvb-usb.ko
Code
$ lsmod
Module Size Used by
em28xx 98304 0
tveeprom 28672 1 em28xx
8021q 36864 0
garp 16384 1 8021q
mrp 20480 1 8021q
stp 16384 1 garp
llc 16384 2 stp,garp
rc_cec 16384 0
vc4 192512 4
cec 73728 1 vc4
brcmfmac 319488 0
brcmutil 16384 1 brcmfmac
drm_kms_helper 208896 3 vc4
drm 507904 3 drm_kms_helper,vc4
smsc95xx 45056 0
rc_core 57344 3 rc_cec,cec
cfg80211 753664 1 brcmfmac
usbnet 53248 1 smsc95xx
hci_uart 139264 0
mii 20480 2 smsc95xx,usbnet
drm_panel_orientation_quirks 20480 1 drm
syscopyarea 16384 1 drm_kms_helper
sysfillrect 16384 1 drm_kms_helper
btqca 20480 1 hci_uart
btbcm 16384 1 hci_uart
sysimgblt 16384 1 drm_kms_helper
fb_sys_fops 16384 1 drm_kms_helper
btintel 32768 1 hci_uart
bluetooth 602112 5 btqca,btintel,hci_uart,btbcm
raspberrypi_hwmon 16384 0
ecdh_generic 28672 1 bluetooth
rfkill 32768 3 bluetooth,cfg80211
pwm_bcm2835 16384 0
bcm2835_v4l2 69632 0
i2c_bcm2835 20480 0
bcm2835_thermal 16384 0
snd_bcm2835 32768 0
bcm2835_wdt 16384 0
videobuf2_v4l2 32768 1 bcm2835_v4l2
m88ds3103 36864 0
videobuf2_vmalloc 20480 1 bcm2835_v4l2
videobuf2_memops 20480 1 videobuf2_vmalloc
videobuf2_common 65536 2 videobuf2_v4l2,bcm2835_v4l2
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As i can see dvb-core depends on media which is also not loaded.