Selling fees have not changed and have been approx 13.4% for years.

Your feedback score is irrelevant.

Paypal have been removed and Adyen have replaced them. As a financial service provider, they legally have to verify you. It is within keeping with Australian rules and regulations and is no different to having been verified by Paypal.

Have you actually double checked that everything matches?

For example, is your registered Ebay name EXACTLY the same as what is in the passport, with no abbreviations and including any middle names? I had an issue because my name was shortened when I signed up 20 years ago and have never had a reason to correct it until Managed Payments came along.

I recommend to stop selling until you have this sorted out.