iPad Air 5th not extending display on old Cinema Display

Greetings all.

I recently bought an iPad Air 5th generation and I'm smoothly using it to extend the display while attached to various external monitors and projectors.

The only exception is with my (very) old aluminium Apple Cinema Display 20": in this case the only possibility is to mirror the display as under "Display and brightness" there is no way to arrange the displays (the option is not visible for such a display). I also tried with or without Stage Manager but no, it does not work.

The Apple Cinema Display has a DVI output, so I have to use a DVI to USB-C adapter to connect it to the iPad Air. That could be the culprit, however the very same adapter connected to a Macbook Pro 2018 allows to use the old Cinema Display as an extended monitor with no issues (and I did it for years, since 2018).

I noticed that under the display settings on the iPad, the monitor is recognised as a "SDR - Standard Dynamic Range" monitor, so I'm not sure if that's an indication the iPad can't use it as an extended display. I also tried to use other different DVI con USB-C adapters, but nothing changes.

Do you think there is anything I can try to use that old display as an extended monitor?

Many thanks for your help,

Antonio