So your using the pos type commands to generate?
Since in theory these tell the printer the code which it then generates the barcode I’m slightly surprised it works in html. In the same way the xct drawer kick code doesnt work in html mode.
Iguess either samba catches and renders or i suspect more likely the print driver.
Are you using supplied printer driver or generic text?
In worst case I can think of a work arround but wouldn’t be very pretty.
In theory you should be able to use scripts to get a qr code image from an online service/api and use the directory for the file within the html. Never tried but should theoretically be posible. However would be better to see what kind of response you get from others more familier with using html for a template format. I have always kept it simple and used pos mode.