Hello! thank you for reporting that, can you please submit a PR.
I will appreciate your contribution on this point.
Thank you.

@lauriejim @aksdevac STRAPI_LOG_LEVEL does work finely inside the logger of strapi. I had checked the variable outputs. The logs is getting printed due to logger middleware which has default value as debug. To change the level, in create/existing config/middleware.js add like this.
module.exports = { //... settings: { logger: { level: "error" }, }, };

It can be also env.
Doc link:
https://strapi.io/documentation/v3.x/concepts/middlewares.html#core-middleware-configurations)

If you want I can submit a PR that checks for the process.env.STRAPI_LOG_LEVEL and take that as log level.

@lauriejim Hi, submitted PR #6701 but it might not fix issue, as middleware is overriding default log level as mentioned in PR & by @akhilmhdh, but can be used for STRAPI_LOG_TIMESTAMP, STRAPI_LOG_PRETTY_PRINT etc

There is another way of making this work. Export your middleware.js with the env object and pass it a default. This way you can make sure your process.env will override it:

module.exports = ({ env }) => ({
    settings: {
        logger: {
            level: env('STRAPI_LOG_LEVEL', 'debug')
        }
    }
})

There is another way of making this work. Export your middleware.js with the env object and pass it a default. This way you can make sure your process.env will override it:

module.exports = ({ env }) => ({
    settings: {
        logger: {
            level: env('STRAPI_LOG_LEVEL', 'debug')
        }
    }
})

This is the correct method