There are two ways you can find if a table used in the Oracle Apex application. Actually, you can find any database object such as procedure, function, and packages, etc. The following are the examples:
Find a Table/DB-Object Using The Search Option in Oracle Apex
Use Oracle Apex search option for application. Follow these steps:
In Oracle Apex, open your application then click on the Search icon on the top right corner as shown in the below image:
After clicking on the search icon, the search box will appear, type the table or any database object name in it and hit enter to find.
Find a Table/DB-Object Using The Exported SQL File
The another way is to find the table or database object using the export SQL file. Follow these steps:
In Oracle Apex, open your application and click on the Export/Import Tab.
From there, export the application in SQL file format.
Open the SQL file in any text editor and find the string containing table or database object name.