My plugin assets are missing the timestamp in the file name

I built a plugin which provides a custom block for the blocks-field type. It comes with a CSS file. Using the information in the docs (plugin-assets) I was able to get it to work and call the right path:

<?= css([
		]) ?>

which generates this HTML on my test server:

<link href="" rel="stylesheet">
<link href="" rel="stylesheet">

According to the docs page linked above the URL should contain a timestamp, but it doesn’t. What am I doing wrong? Do I need to register the CSS file in the plugin’s index.php?

Also, is there a way to use the css('@auto')-feature to only include the CSS file when it is actually needed?

Still looking for a solution too: Plugin asset url helper?

Oh, if its a three year old problen, it should probably move to Github as an issue? Maybe @texnixe can advise if we should move this to Github?

Yes, that would make sense.

GH issue here: Plugin asset CSS files are miss timestamp in URL · Issue #5164 · getkirby/kirby · GitHub