I was getting this error:

[23081.890579] usb 3-3: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[23081.890580] usb 3-3: Product: USB Serial
[23081.892947] ch341 3-3:1.0: ch341-uart converter detected
[23081.893472] usb 3-3: ch341-uart converter now attached to ttyUSB0
[23085.798948] usb 3-3: usbfs: interface 0 claimed by ch341 while 'brltty' sets config #1
[23085.799730] ch341-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0
[23085.799756] ch341 3-3:1.0: device disconnected

Fortunately I found this solution: https://unix.stackexchange.com/questions/670636/unable-to-use-usb-dongle-based-on-usb-serial-converter-chip

for f in /usr/lib/udev/rules.d/*brltty*.rules; do
    sudo ln -s /dev/null "/etc/udev/rules.d/$(basename "$f")"
done
sudo udevadm control --reload-rules

And disabling the service:

$ sudo systemctl mask brltty.path
Created symlink /etc/systemd/system/brltty.path → /dev/null.

It worked, now /dev/ttyUSB0 keeps on!