TYPO3 Core

Actually the fix is easy, as admin you can follow this hint to add the functionality, note my comment below too before doing anything:
https://stackoverflow.com/questions/76168846/how-do-i-activate-the-font-functions-in-ckeditor-5-in-typo3-12

The plugin has to be added in 2 places in `typo3/Build/Sources/JavaScript/rte_ckeditor/contrib/ckeditor5-bundle.js`, below the previous and next lines are shown to know where:

import Table from '@ckeditor/ckeditor5-table/src/table.js';
import TableCaption from '@ckeditor/ckeditor5-table/src/tablecaption.js';
import TableToolbar from '@ckeditor/ckeditor5-table/src/tabletoolbar.js';

export const CKEditor5Plugins = {
  ...
  Table,
  TableCaption,
  TableToolbar,

For compiling with npx and grunt I did the whole process in DDEV, so I never had to care about any version, it's usually just working.

The plugin tablecaption still has to be included in the yaml configuration for the editor:

editor:
  config:
    toolbar:
      items:
        ...
        - insertTable
        ...
    table:
      defaultHeadings: { rows: 1 }
      contentToolbar:
        - tableColumn
        - tableRow
        - mergeTableCells
        - tableProperties
        - tableCellProperties
        - toggleTableCaption

The plugin tablecaption is removing the tag caption but wrapping a table in the the code:

<figure class="table">
<table>
...
<table>
<figcaption>HERE IS THE CAPTION</figcaption>
</figure>

styles {
    content {
        allowTags := addToList(figcaption)
    }
}

Patch set 8 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 9 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 10 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 11 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 12 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 13 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 14 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 15 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 16 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 17 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 18 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 19 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 20 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 21 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 22 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 23 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/79006

Patch set 1 for branch 12.4 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/81397

Patch set 1 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/82185

Patch set 2 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/82185

Patch set 1 for branch 12.4 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/82187

Patch set 3 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/82185

Patch set 4 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/82185

Patch set 2 for branch 12.4 of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/82187