because of Covid, EAs can no longer do group viewings. In addition they now have to supply rinses and PPE to viewers. It is now not possible to offer every enquirer an appointment at an open viewing and sounding them out.
A viewing is now a significant overhead for an EA and it is reasonable to limit viewing to enquirers who have at least started the ball rolling with a bank and still have approval.
Fortunately I don't see how it's supported by existing data protection legislation.
Many businesses are facing increased costs as a result of social distancing/additional hygiene requirements. Most still have to operate within the law.
Maybe the DPC will come back to the OP and tell them that GDPR has been suspended or is not being enforced in the current environment. You never know.
If an EAs costs have increased as a result of measures taken, I would have though it more appropriate to either increase charges to vendors or charge for viewings. No unnecessary personal data required for either of those options.