You have some really dirty hacks in your composer.json. A line like `"drupal/core": "9.2.3 as 8.9.0"` is a very bad idea and is always going to explode sooner or later. The intention usually is to upgrade Drupal core v9 while keeping v8-only/v9-incompatible modules, but trying to do something like this is just plain wrong.

 1. Remove all lines `drupal/core***` except `drupal/core-recommended` and `drupal/core-composer-scaffold`. Those two will require all other stuff, the superfluent `drupal/core***` just make future upgrading harder.
 2. In your other post there is the error message `...drupal/theme_switcher 1.1.0 requires drupal/core ^8.5...`. This module is incompatible with Drupal v9 (and maybe has been the cause for the very bad idea mentioned in earlier). Luckily there is now a `drupal/theme_switcher:^1.2` which is compatible with Drupal v9.
 3. In my experience the most reliable way to update Drupal core is to explicitly require a new minimum version of core-recommended and core-composer-scaffold: `composer require drupal/core-recommended:^9.2.4 drupal/core-composer-scaffold:^9.2.4 --update-with-dependencies`.
 4. In your special case you also need to update the v8 Theme switcher module to get a full set of v9 compatible packages: `composer require drupal/core-recommended:^9.2.4 drupal/core-composer-scaffold:^9.2.4 drupal/theme_switcher:^1.2 --update-with-dependencies`