TYPO3 Core

with the old composer installer and previous TYPO3 versions it was possible to install typo3 in a way, that resources are loaded from

public/typo3conf/ext/

With the newer core and the same old installer (v3) this works fine as long as you use composer in the root folder and do not use the constant TYPO3_PATH_ROOT, otherwise the resources are loaded from

_assets

The change happend somewhere in the v11 releases, will try to pin that down further.

Worked for v9, v10, upgrade to v11 broken

Btw. for v12 we switched to the

_assets

Helmut Hummel wrote in #note-3:

I assume TYPO3 11, like set to the bug report. correct?

Yes, correct.

and the installation using enviroment variable: TYPO3_PATH_ROOT,

Can you explain what you want to achieve with setting this environment variable in Composer mode
and especially to what value you are setting this compared to the value that TYPO3 calculates for this path?

In this setup, the vendor (and a few other) folders are not in the document root. The variable is set to the document root. This worked fine under v9 and v10.

In general changing these environment variables is discouraged, as it bypasses all validation that happens, when configuring the paths via composer.json settings. Violating validations, will lead to unexpected behaviour.