I was being dumb and tried to change trade offer to deposit items to the bot before realising there was a another way to do deposits. So I cancelled the trade offer since dispenser bots weren't accepting it.
I thought that after 10 mins it would be cancelled and I'd be able to withdraw the Dota keys again (and without messing with it) but it seems to be stuck (Dota keys are greyed in my Dispenser.tf inventory and the transaction still appears in the footer of pages on the website after almost 30 minutes)

Hoping an admin can fix this and sorry for the inconvenience

Edit: it got fixed today, either thanks to admins or the daily CRON task ;)