Unfortunately this is never as simple as its seems.
I purchased a new OLED TV in January to replace a model from the same manufacturer which the original had an optical output providing 24Bit 48 Khz. The new model £1500 has only 16 Bit audio on optical and so I contacted the manufacturer to confirm what bit depth and sample rate the new model could provide from its 'arc' output - I am still waiting a response despite multiple communications suggesting that I read the manual and tech spec which has absolutely no reference to this
Obviously the manufacturer is not concerned about sound quality or customer service?
This isn't a forum to name and shame, however a message to manufacturers "If your to sell technology, please ensure you and your support staff understand it!
The information at the end asks the question "Is eARC backwards compatible with ARC?" An explanation is given which is fine & correct, but then it states "So no, it's not backwards-compatible."
Well, yes it is backwards compatible - you can plug in older equipment and it will work. No one is going to think that you can plug older equipment and suddenly get better features on it.
The same mishmash as with everything in the home entertainment industry. Manufacturers are trying to push you to buy something amazing that will open up unsuspected worlds to you - and which will be "out" again in a few years ...