Right to rent checks are standard, because it is illegal to rent to someone who does not have a valid visa, and the landlord can get an unlimited fine and even be sent to prison if they do.
So, basically, they're just covering their backs.
A right to rent check involves the estate agent checking that your passport and BRP are valid and genuine.
From the official UKVI guidance:
Check their original documentsYou need to check that:
- the documents are originals and belong to the tenant
- their permission to stay in the UK has not ended
- the photos on the documents are of the tenant
- the dates of birth are the same in all documents (and are believable)
- the documents are not too damaged or do not look like they’ve been changed
- if any names are different on documents, there are supporting documents to show why, such as a marriage certificate or divorce decree
See:
https://www.gov.uk/check-tenant-right-to-rent-documents/how-to-checkUpdated guidance during Covid:
https://www.gov.uk/guidance/coronavirus-covid-19-landlord-right-to-rent-checksAlso:
https://www.gov.uk/landlord-immigration-check