Rent reductions

I’d love to hear people’s experiences regarding tenants asking for reduction in rent. During lockdown my tenants asked for a decrease in rent due to one of the 3 (who technically wasn’t my tenant as he was a sublet which I’d agreed) lost his job. One of the named tenants also took 20% pay cut. Anyway we agreed a 3 month reduction which we asked to recoup after the 3 month reduction by raising the rent by a small amount. Even though we were happy to give them a reduction of £400 they always gave more. As lockdown continued they asked for another month of lower rent. As soon as we got to a new rental price one of the tenants gave notice so I’m now having to draft a new contract for the remaining tenant who still wants his sublet agreement and has found a new people to join him on the lease. HOWEVER he’s asked for a temporary rental reduction of 20% which is over £400 with no debt accrued and for a 6 month period. He’s also asked for a 6 month lease. I own a 3 bed flat in E9, Hackney Wick. The lead tenant I’m talking to has lived at the flat for 2 years and been great but I want to make sure he’s not asking for too much. I’m happy to negotiate a reduction but need to get a sense of what’s feasible. Typically flats in my area would go in a flash but from the Openrent listings I can see most are still around the value I’m looking but many have had to put in reductions so they also fall to value the tenant is asking. Any advice or thoughts from other landlords? I’m thinking to contact an Estate Agent to get further intel on the market but would really welcome other’s advice.