Steps to reproduce:

1. Install Oracle Database 12.2.0.1.210720 (Jul 2021) on DB server
2. Create Oracle Database with: CHARACTER SET AL32UTF8 and NATIONAL CHARACTER SET UTF8
3. Create user "zabbix" wiith DBA privs
4. Use recommendations from ZBX-19717 to increasing max_string_size (alter system set max_string_size=extended)
5. download sources "https://cdn.zabbix.com/zabbix/sources/stable/5.4/zabbix-5.4.4.tar.gz" and extract
6. use sqlplus 12.2 on DB server machine or sqlplus 19.12 from instant client on clent machine
7. execute database/oracle/schema.sql
8. execute database/oracle/images.sql
9. execute database/oracle/data.sql

Result:
See screenshot
See log file...

Expected:
Database schema create on Oracle