Are you using a browser or the eBay app?
It is possible that if you have the app it is trying to open eBay item browser links automatically. If the app version is old, it may not work correctly, so make sure you have the latest version.
Or else change your settings so that eBay browser links do not open in the eBay app.
The last time I used a Chromebook, the following worked to change the default app behavior:
Open Chromebook Settings, scroll down to Google Play Store and select it. Select "Manage Android Preferences". From there go to Apps: eBay: Open by default: Open supported links and choose: "Don't open in this app". Then back out of the settings and you should be all set.
Or else, open Chromebook Settings, and select Apps. Select "Manage your Apps". From there go to eBay: More Settings: Advanced: Open by default: Open supported links: "Don't open in this app".
If you do not have the eBay app on your Chromebook, try another browser to rule out browser issues.
If pages load correctly in another browser, try clearing your cache and possibly eBay cookies in the original browser.
