Your money is not protected in Revolut.
They are not covered by the Uk gov guarantee up to 85k due to not having a Uk banking licence. Saying they keep it with a tier 1 institution is like anyone else saying they keep the money you’ve lent them in a bank.
They claim to have a European banking licence but due to the legal complications this does not actually mean much.
I still use it to transfer cash but try to get in and out as quick as possible. Storing cash in Revolut is a risky strategy.