cache_container table is not empty after clear the cache

table cache_container not truncate when clear cache, the problem affect at Drupal core 10.3.1,

steps to reproduce
1- clear cache drush cr
2- drush sqsl-cli
3- select * from cache_container the table is not empty

cr means cache:rebuild. It doesn't only clear the caches. It rebuilds them:

Rebuild all caches.

This is a copy of core/rebuild.php.

Options:
 --cache-clear[=CACHE-CLEAR] Set to 0 to suppress normal cache clearing; the caller should then clear if needed. [default: true]
 --no-cache-clear            Negate --cache-clear option.

Global options:
-v|vv|vvv, --verbose Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug
-y, --yes            Auto-accept the default for all user prompts. Equivalent to --no-interaction.
-l, --uri=URI        A base URL for building links and selecting a multi-site. Defaults to https://default.
                     To see all global options, run `drush topic` and pick the first choice.

Aliases: cr, rebuild, cache-rebuild

So it is working properly. Why is this a bug?

If you don't have a container, you don't have a site

The cache rebuild rebuilds the container so your site works

When dumping the database, the database file is very large. The database size is 50 GB, but after I truncate the cache tables, the database size reduces to 350 MB.

Here are the commands I used on the database:

TRUNCATE cache_bootstrap;
TRUNCATE cache_config;
TRUNCATE cache_container;
TRUNCATE cache_data;
TRUNCATE cache_default;
TRUNCATE cache_discovery;
TRUNCATE cache_dynamic_page_cache;
TRUNCATE cache_entity;
TRUNCATE cache_menu;
TRUNCATE cache_page;
TRUNCATE cache_render;
TRUNCATE cache_toolbar;
TRUNCATE cachetags;

Without having some idea which of those tables is large and why, it's difficult to advise.