In 1.13-pre6, changes were made to the fonts in Minecraft which affected obfuscated text.
The bug
Since 1.13-pre6, obfuscated text now uses a severely limited character set (looks like just the ASCII character set) whereas it previously used a rich character set of accents, letters, symbols, and other peculiar characters.
I have uploaded a video which shows the effect in 1.13-pre5 and 1.13-pre7. The video is at 25% normal speed but you can also view it frame-by-frame or test yourself.
How to reproduce:
On either version of Minecraft, enter:
/tellraw @a {"text":"abcdefghijklmnopqrstuvwxyz1234567890","obfuscated":true}Note
This bug may also relate to MC-132664, which covers obfuscated text not randomizing.
Linked issues
relates to 2
Attachments
Comments 2
Apparently it only loads the characters the game has rendered while it's been running, and that includes characters that aren't in ASCII as well, too (also some with the legacy unicode font, it didn't do that before).
Try to reproduce while language is set to English and you haven't opened the language menu yet. Then write a special character into the chat, for example ä or ß. The character will start to appear in the obfuscated text. After you open the language menu, all sorts of characters start to appear, but only those that also appear in the language menu.
bugmancx
I have noticed a similar issue that I don't think merits a new bug report since it is closely related to this, but the subset used for obfuscated text seems to grow after typing valid characters in chat, at least for 1.13 prerelease 8. What I mean by this, is that whenever I open a new instance of Minecraft and load up my world, if I use the command (only tested with titles): /title @a title {"text":"l","obfuscated":"true"}, which uses a lowercase L for the text, there is nothing being changed in the L because the game doesn't have a valid characters recognized off the top of its memory. I think this may be due to it being 2 pixels wide, which seems to be the only character of similar width loaded upon startup. However, if in chat I type the grave tick symbol (`), this character is also 2 pixels wide. Now, if I repeat the same command above, the grave tick symbol is used to obfuscate the L, switching between the two. If I leave my world and re-enter, it will still use the grave tick to obfuscate the L. If I restart my entire instance, however, it will not use the grave tick again.