public interface IDapperContextBuilder
{
    IDbConnection  CreateConnection();
}

[Fact]
        public void GetAllAuthority()
        {
            // Arrange
            var connectionFactory = Substitute.For<IDapperContextBuilder>();
            var fakeConnection = Substitute.For<IDbConnection>();
            connectionFactory.CreateConnection().Returns(fakeConnection);
            // Simulate Dapper behavior
            var authority = new MasterData.Authority();
            fakeConnection.QueryFirstOrDefaultAsync<MasterData.Authority>(Arg.Any<string>()).ReturnsForAnyArgs(authority);
            // rest of the code
        }

public async Task UpdateStatus(AuthorityStatusUpdateInputDto input)
{
    
    using var connection = _dapperContextBuilder.CreateConnection();
    Authority authority = await connection.QueryFirstOrDefaultAsync<Authority>(SELECT TOP 1 * FROM Authority");
    // rest of the code
    
}

Can not return value of type Task`1 for IDbCommand.set_CommandText (expected type Void).
Make sure you called Returns() after calling your substitute (for example: mySub.SomeMethod().Returns(value)),
and that you are not configuring other substitutes within Returns() (for example, avoid this: mySub.SomeMethod().Returns(ConfigOtherSub())).
If you substituted for a class rather than an interface, check that the call to your substitute was on a virtual/abstract member.
Return values cannot be configured for non-virtual/non-abstract members.

var connectionFactory = Substitute.For<IDapperContextBuilder>();
            var fakeConnection = Substitute.For<IDbConnection>().SetupCommands();
            
            connectionFactory.CreateConnection().Returns(fakeConnection);
            var authority1 = new Authority() { Id = 1, Name = "N1" };
            var authority2 = new Authority() { Id = 2, Name = "N2" }  ;
            
            fakeConnection.SetupQuery("SELECT * FROM Authority").Returns(authority1, authority2);