[SOLVED] 11.x and 12.x shows HTML tags in blog posts

posts: 9 Hungary

After I've recently upgraded from tiki-10.3 to tiki-11.0, I experience the problem mentioned in the title. HTML tags shows up in blog posts instead of being interpreted. I've executed the database upgrade as usual without any error messages.
I could find no relevant configuration setting in the admin panel.
There were a relevant google search result, but without any obvious solutions mentioned:
What should I check out?
Now I reverted my database and installation and moved on to 10.4 instead. Blog posts shows up fine without any HTML tags.
Is this an intentional behavior? Should I convert HTML tags in blog posts in some way while moving to v11.0?

Please let me know how should I properly deal with this symptom or any further information you need for giving me advice.

Thanks for all the developers and the community for creating this great software:

posts: 9 Hungary

This problem also persists for 12.x
The solution came from lindonb on IRC:
putting the blog post content within PluginHTML tags - i.e. \{HTML()\}content\{HTML\}
(without backslashes - I'm just escaping the contents)
On my site it requires approval after that, but I don't have so many affected posts.