Obviously this will not be implemented as a Sniff. But our tool should ease TYPO3 updates in all possible ways. One would be to check the database. Are you including css_styled_content which is no longer available?

Therefore we should probably provide different tools, one providing phpcs standards as already done. One providing db migrations, a distribution to bundle all together, etc.

We should implement the css_styled_content as a first example to kickstart the architecture and feature to check the database.

Once that's implemented, create issues for the following tasks:

• Apply TypoScript checks to database, see #54 (closed)
• Apply PageTSConfig checks to database, see #54 (closed)
• Apply UserTSConfig checks to database, see #54 (closed)
• Check whether removed fields contain something that will be lost during migration?
• Check what TYPO3 does between the versions to create further related issues.