BUG #16907: Performance issue after big table drop and recreate

The following bug has been logged on the website:

Bug reference: 16907
Logged by: Rahul Namdeo
Email address: namdevrahul@gmail.com
PostgreSQL version: 10.15
Operating system: NAME="Ubuntu" VERSION="18.04.3 LTS (Bionic Beaver)
Description:

1. Took pg_dump of 580 GB table with no data.
2. Rename the original table to TABLE1_original
3. Dropped the five indexes approx 1.2 TB on this table.
4. Did a pg_restore from the backup taken.
5. Created the indexes / constraints and provided all the grants as
required.
6 Run the Application process for report generation. It took 25 mins for
single day report which was expected behavior.
7. However after 3-4 days run the performance was degraded and the same
report now takes 2.5 Hours.

Any help will be appreciated. Kindly support.

NOTE: the Environment is on AWS Cloud Server is M5.4xLarge (16 Core 61 GB)