The down arrow in the keyboard gets pressed automatically.

[Clerissa]

HP LAPTOP 15-DB1069AU AND RYZEN 3

[BeemerBiker]

Need to make sure the problem is the keyboard and not something in windows or (for example) a defective Bluetooth mouse nearby that make the cursor move down.

Try to get into the BIOS setup.  Press ESC after power on or F10 and get into the setup

Is there still a problem with the key?

If the problem is the keyboard you can try looking at the down cursor key and also the #2 keypad key

There is a larger picture of your keyboard here

and a service here that sells replacement keys and shows how to replace a key.   

https://www.replacementlaptopkeys.com/hp-pavilion-15-db-keyboard-key-replacement/

The video may not match exactly your DB-15

Try lifting up the key both the down cursor and the #2 keypad and see if that stops the problem.

You can check your warrantee here

and get it repaired here

1) Click on this link -
https://support.hp.com/us-en/contact-hp
2) Select your product type below.
3) Enter the serial of your device.
4) Select the country from the drop-down.
5) Select the chat or get phone number options based on your preferences.
6) Fill the web form and proceed further.
To obtain parts (if not using ebay) use this list:
https://parts.hp.com/hppartsIGSO/Part_Resellers.aspx?from=ERP&cc=GB〈=EN&geo_code=EMEA