BUG #16211: Disk space keep rising for originated tablespace of base Database - Mailing list pgsql-bugs

The following bug has been logged on the website:

Bug reference:      16211
Logged by:          Gen Eva
Email address:      mail4yura2@gmail.com
PostgreSQL version: 12.0
Operating system:   Windows 7 64
Description:

0) create some simple Database, named "DB1" on "DdiskTablespace" and review
its physical memory size storage.
1):
CREATE DATABASE "DB2" 
TEMPLATE "DB1"
TABLESPACE "EdiskTablespace"
;
2) Review "DdiskTablespace" its physical memory size again for "DB1"

Actual res: 
Size for "DdiskTablespace" has grown up
Expected:
Size for "DdiskTablespace" for "DB1" remains the same as for step 0.
Only new "DB2" tablespace "EdiskTablespace" grown.