I'm a little confused that the exclude isn't respected anymore. From a quick glance all errors are from example.php or *Test.php which both should be excluded.

<rule ref="src/Sniffs/StrictTypes/ExplainStrictTypesSniff.php">
  <exclude-pattern>*/*Test\.php</exclude-pattern>
  <exclude-pattern>*/.meta/*\.php</exclude-pattern>
  <exclude-pattern>src/*</exclude-pattern>
  <exclude-pattern>contribution/*.php</exclude-pattern>
</rule>

Well, looks like the sniff name generation has gone wrong and so the excludes are not applied for our sniff. Would you mind opening an issue at PHPCodeSniffer and report the problem?

It's now working ready for review.

I'm personally self in doubt about the src/Exercism/ directory, if that should be called something else.

Which version of PHP CodeSniffer is required as a minimum, so that the name change works with the exclude-pattern? This should be set in composer.json "require-dev": { "squizlabs/php_codesniffer": "^3.11.?" } accordingly.

3.11.1, I'll update composer.json too.