Am I in legal limbo?

Hello! I’m looking for opinions / advice on what type of contract situation I’m in and what would happen if my landlord served notice.

For context, my flatmate and I had as AST that ran out in 2019 and turned into a statutory periodic tenancy. Due to Covid-19 my flatmate moved out in June and the landlord gave us both the deposits back. The landlord let me pay my normal rent, but now that it’s difficult to find a new flatmate he is demanding I pay double rent.

From what I’ve read, because he returned the deposits the contract tenancy has ended. We should have signed a new agreement, but apart from a few emails (nothing legally signed) there’s no formal agreement that I should pay both rents. The landlord has hinted that he might serve me notice and that it would be 1 month. My understanding is Section 21 is currently 3 months, even for a statutory periodic tenancy (which I don’t think we even have due to the deposit being returned).

Am I tenant or just someone living in his property paying him money every month? If I am still on a periodic tenancy, would I get 1 months notice or 3 months due to Covid?

i am not an expert but just because the deposit is returned does not end the tenancy On some tenants I take no deposit anyway but they are still a tenant You pay monthly you are a tenant. Poss you can find a flatmate?