It’s a fundamental problem of misaligned incentives between the employee and employer.

It is in the interests of the employee to have a more defensible position, even if it increases employer risk.

Which means you need to find a new employer. There are companies and/or managers out there that don’t have these misalign incentives, encourage best practices (like those in this blog post), and provide psychological safety. They exist.

The incentives are misaligmed at fundamental level. If manager could fire you while still getting the same job done they would.

Your best defence are your capabilities. Being “indispensable” means nothing if the company goes under.

Exactly. If you increase team productivity and your boss fires you for it instead of promoting you, then the company is doomed so why would you want to work for them?