BGP Routes

We’re currently running BGP with our service provider and at the same time peering with 2 customers. We’re receiving the full BGP table from our service provider and want to advertise this full table to only one of the customers while a default route is advertised to the other customer.

Is there a way I can implement this on RouterOS 5.21 ?

Yes, set up routing filters to drop all routes going to second customer. And on second customers peer config set option originate-default.