Have you created a menu item for the category of the article, or a List All categories menu item?
If not, test that.

Take a look at the nice list:
#22450
#22036
#21935
#20892
#20242
#19997
#19729
#19537
#19497
#18818
#18771
#17719
#17096
#16496
#14175

I prepared PR to solve that on J4 but the is no testers for #22229

I can prepare similar PR for J3 but it requires more people to be involved. Testers are needed. Last time when I did it, I made a few mistakes and PRs were reverted in J3.8.5.

Yes menu item for the category of the article Menu Item Type > Tagged Items

but Actual result still is

/?view=article&id=54:brin-te&catid=12

@infograf768 can you be more specific how to test this or is there a documentation ?

@csthomas the list of bugs is big please please prepare similar PR for J3 if it solves this joomla bug

Do you have URL Routing set to Modern?

Yes URL Routing set to Modern

My PR would only replace /?view=article&id=54:brin-te&catid=12 by something like /component/content/article/54:brin-te?catid=12 or /component/content/article/12-your-category-alias/54:brin-te.

If there are more people interested, I will try to find more time to do it.

If you want to have a nicer URL, you need to set the menu item for each top category or for categories view. You should find more information in mentioned issues above.

@csthomas @infograf768 so it is imposible to make

Expected result
/small/drop-number/brin-te
Actual result
/?view=article&id=54:brin-te&catid=12

after pr the best joomla can make is /component/content/article/12-your-category-alias/54:brin-te. ? not /small/drop-number/brin-te ?

You can't use one component (in this case com_tags) to automatically build an URL for another component (com_content). You can only do this manually by making the article a child menu item of Tagged Items menu item. You'd have to do this for every article tagged with your tag. To avoid that, you should use Categories, not Tags, to structure your site.

Without the appropriate menu items it is impossible. Please read mentioned issues to see what options do you have. @SharkyKZ's comment is correct.

I suggest to take a look at #22450 (comment) . As the home page, you can set the category view for "Top Category". Other categories move into "Top Category".

@SharkyKZ could you please explain what is the correct way to get this using tags?

Expected result
/small/drop-number/brin-te
Actual result
/?view=article&id=54:brin-te&catid=12

@infograf768 is there documentation on how these Tagged Items should work using modern routing?

This imho is not related to tagged items, it is a general issue with Modern routing.

Until @csthomas patch is tested and does work without B/C issues, the best solution [again] is to create a List All Categories menu item, even hidden, as a root menu item in your menu.
Let's say this menu item alias is listallcat

You will never get anyway
/small/drop-number/brin-te

but
/listallcat/brin-te

I mean if you do not have a direct menu item to the article.

@infograf768 After you create a menuitem for the tag you still get /component/tags/tag/tag-name when you click on article and scrool down to the tag.

What are your steps to reproduce /tags/tagname ?

I have menu item with category blog. Category contain 45 articles. When i press to this menu item i see 10 articles. And all these articles have same tag. It looks like that tag filter is applied.
If i will manually go to links with ?filter_tag[0]="something" i can change set of articles in the blog without filters. It looks like filtering is applied and stored somewhere when i try to look on list of all articles.

Is it same error? Or i should create new bug report?

@radioagent Your issue is different. The filters are applied in menu item - go to backend, edit the menu item and select/deselect tags.

@Hackwar can you please comment about the Router-Aspects?

This is expected behavior and your website is not correctly configured. Even if @infograf768 thinks it's wrong, you still have to create menu items for your content, otherwise you get crap URLs. That the tagging system is also crap, is a different story. I wouldn't know what else to say about this.

@Hackwar please be careful with your words

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/22589

@Hackwar thanks for Comment, closing Issue.