Hive account@ninki.vienna Sorry for the late reply, had no time resource time to check and find why < center> tag bugs.
I was able to recreate what you are describing. It is dependent of lines with blank spaces.
If you put both center tags in a single line it works fine just like that.

You can also use center in multiple lines, but you should never leave a empty line. Example:

And leaving just a single empty line produce a BUG and everything below gets centered

for example

< center>
line of text
⠀
second line of text with blank line above
< /center>
Uncentered text

This example would make all the text centered, even the "uncentered text" below the closing tag.

You can fix this with a < div>

< div class="text-center">
test line 1

test line 2
< /div>
uncentered line outside of div

To make the above example work, remove the blank space from the opening and closing div tags.