Error 500 when Redis is enabled in Osclass 8.3.0

I am running Osclass 8.3.0 on PHP 8.3. I get the following fatal error on every page load when Redis is enabled:

PHP Fatal error: Uncaught TypeError: Cannot access offset of type string on string in:
core/osclass/model/Category.php:329

Stack trace:
#0 core/osclass/model/Category.php(77): Category->toTree()
#1 core/osclass/model/Category.php(41): Category->__construct()
#2 core/osclass/helpers/hCategories.php(97): Category::newInstance()
#3 core/osclass/controller/search.php(553): Field->findIDSearchableByCategories()
#4 index.php(276): CWebSearch->doModel()

I have:

Cleaned all caches (file, Redis, OPcache)
Verified database integrity
Confirmed no corrupted category parents
Tested on PHP 8.2 and PHP 8.3 — same error
No theme overrides or plugins installed
This error occurs in the core Category.php file in a fresh install of Osclass 8.3.0.

This is a critical bug preventing any site from loading.

Please advise if this is a known issue, or provide a patch, or what to do.

Thanks.

If you have Redis enabled and you are sure it's OK and correctly setup in config.php and you still have issues, send us PM with url, ocadmin and ftp login and we will look on it.