Codeigniter 4 V 4.5.1 $this->db problem

You're too telegraphic and I don't understand, I would like to understand how to get back to having the same thing as before the update but in the correct way.

What version did you upgrade to 4.5 from?
My understanding is that there are no particular breaking changes,
so I'm not sure why your code would stop working with the upgrade.

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper