How to find dropped or ghosted columns in Azure SQL DB?
Since Azure database is MSSQL server then you can execute the following command to find how many ghost process per database

SELECT sum(ghost_record_count) total_ghost_records, db_name(database_id) 
FROM sys.dm_db_index_physical_stats (NULL, NULL, NULL, NULL, NULL)
group by database_id
order by total_ghost_records desc


And if you are looking for more detailed report then you can execute the following command

SELECT
db_name(database_id),
object_name(object_id),
ghost_record_count,
version_ghost_record_count
FROM sys.dm_db_index_physical_stats(DB_ID(N'db_name'), OBJECT_ID(N'table_name'), NULL, NULL , 'DETAILED');


Looking for long term solution to start recording this data then you can check this post. This will create table that store ghost records in the long term, but I recommend you to create it on test environment first to see if this is what you actually want.