This is what our friend Google says.......

Yes, you can sell a barometer on eBay UK, provided it is an aneroid barometer (which uses mechanical parts, not liquid). Due to strict hazardous materials policies, eBay strictly prohibits the sale of any item containing liquid

looks like you will have to sell it elsewhere 😞    Do not keep relisting it and having it removed.    Doing this can/will result in Ebay either temporarily or permanently banning you from selling on the site.

If others like yours are listed.......probably because as yet Ebay have not noticed and/or they have not been reported.