Trouble after updating to 2.0 I got a notice to update composer to 2.0 today and gave it a try, using &quot;composer self-update --2&quot;. Now when I run composer update, I'm seeing this message.

The &quot;grasmash/composerize-drupal&quot; plugin was skipped because it requires a Plugin API version (&quot;^1.0.0&quot;) that does not match your Composer installation (&quot;2.0.0&quot;). You may need to run composer update with the &quot;--no-plugins&quot; option.

I then tried installing colorbox and see &quot;drupal/colorbox&quot;: &quot;^1.6&quot; in composer.json, but it does not appear when I refresh the extend page; is this related to the above problem?
Next, I tried updating core from 8.9.6 to 8.9.7, following a message I saw, I tried composer update drupal/core-recommended --with-dependencies -W --no-plugins and now I see this message.
  Problem 1
    - Root composer.json requires composer/installers ^1.2 -&gt; satisfiable by composer/installers[v1.7.0].
    - composer/installers v1.7.0 requires composer-plugin-api ^1.0 -&gt; found composer-plugin-api[2.0.0] but it does not match the constraint.
  Problem 2
    - composer/installers v1.7.0 requires composer-plugin-api ^1.0 -&gt; found composer-plugin-api[2.0.0] but it does not match the constraint.
    - signature_pad/signature_pad 2.3.0 requires composer/installers ~1.0 -&gt; satisfiable by composer/installers[v1.7.0].
    - signature_pad/signature_pad is locked to version 2.3.0 and an update of this package was not requested.

I don't understand all these errors, and I am afraid to do anything else. How do I get out of this without reverting composer to 1.x?
grasmash/composerize-drupal is used to convert a Drupal site that wasn't created with Composer into a Drupal site managed with Composer.
Once the plugin converted the site, it can be removed. After the plugin is removed, modules and themes must be added with composer require, not downloading the archive containing the module/theme files.
If that is the only plugin that isn't compatible with Composer 2.x, you can remove it, as it's not necessary to keep it installed.
Drupal 8.9 is compatible with Composer 2.x; it should not create issues with that Composer version.