I ditched Tesco for Asda.
Even though I was a weekly online customer of Tesco's for 13 years from 2007-2020, they never offered me a delivery slot during the lockdowns. However, as a new customer of Asda (never used them before), they offered me a slot every week without fail. So yes there is no such thing as customer loyalty i.e. 13 years vs 0 years, but I have stuck with Asda as of December 2022 (and just renewed my yearly delivery contract) out of principle.