Changes show on the right. Download the image, then add it as a panel that links to your tip page.
Twitch: your channel page → About → Edit panels → + → Add a text or image panel → upload the image, paste your tip page as the image link → Submit.
Kick: your channel → About → Edit → add a panel → upload the image, paste your tip page as the link → Save.
On stream: add the QR card as an image source in OBS so viewers can scan it with their phone.
The images are made at double size so they stay sharp; Twitch and Kick scale them to the panel width (320).