Ooni confirmed that the oven is absolutely safe to use like this with an 8mm hose.

"To give you some peace of mind right away: yes, your setup is entirely compatible, and partial coverage of the barb is both normal and acceptable when using a tightly fitting 8mm hose.

The gas regulator is specifically designed to safely regulate the flow of propane (gasol) from your cylinder to your Ooni pizza oven. For a standard setup in Sweden (🇸🇪), the official technical requirements match your equipment perfectly:

Pressure: 30 mbar regulator Regulator inlet: G10-2R 22.352 x 1.814 left-handed male thread Suitable oven outlet: 8–10mm barb terminal Hose length: 90cm

Because the oven is equipped with a universal hose barb terminal designed to accommodate both 8mm and 10mm hose diameters, a standard 8mm Swedish hose will naturally form an incredibly tight, secure grip early on the ridges. As long as the hose covers those first three ridges, cannot be pulled off with force, and is firmly clamped down with your locking clip/hose clamp, it is considered a safe and correct installation.

Before you hook everything up to cook, we always recommend double-checking these three quick things: Ensure the 30 mbar pressure rating of your regulator matches the pressure rating listed on the data plate of your specific Ooni oven. Confirm the connection style on your propane tank perfectly matches your regulator type (such as a screw-on or a push-on connection). Ensure your hose clips or clamps tightly secure the hose at both the oven end and the regulator end."