https://wiki.postgresql.org/wiki/Index_Maintenance

Quick conclusion: never EVER use VACUUM FULL for index rebuild . It will break the indexes, if you use VACUUM FULL you'll have to REINDEX all the table indexes…

THE repository:
https://github.com/ioguix/pgsql-bloat-estimation

Additional official pages:

• https://www.postgresql.org/docs/current/routine-vacuuming.html#AUTOVACUUM
• https://www.postgresql.org/docs/12/routine-reindex.html
• REINDEX syntax