here is a solution for efficiently backing-up your Airtable base using Integromat
this solution uses only 5 operations per 100 records and can therefor manage many records and backup runs even with the frre plan of Integromat. It can also easily be expanded to include encryption and various types of triggers and the backups can also be done to various other medium i.e. gsheets, MySQL etc.
See details for the solution here - https://5im.pl/airbac