You still have a store.

And the app, while it has many issues, is unlikely to contain a virus. Which would appear to be your problem. Have you run AV and Malware checks? If not, why not? Or do you simply assume that it is an eBay issue when you are the only one so affected?

My store is not affected, nor are my other 2 accounts, so it would seem to be an issue with your phone. Given you CAN access eBay using somebody else's phone, that would be indicative.