Hi, welcome to Spider ID. 🙂 This looks like Steatoda paykulliana.
Is it poisonous?
My understanding of Steatoda venom is that it’s similar to but significantly less toxic to people than that of a Black Widow’s (Latrodectus) – everyone’s immune system is different though. So while they’re unlikely to bite except in self defense and are not anything to worry about they’re still worthy of some respect.