Preventing -Redacted- characters in username

[Orit]

Hello
Quite a few of our users are recently changing their usernames to usernames containing emojis and other unicode characters.
Is there a way to prevent that?

I don't really mind them using those characters, but we get server errors regarding those changes:
XF\Db\Exception: MySQL query error [1267]: -Redacted- mix of collations (utf8mb3_general_ci,IMPLICIT) and (utf8mb4_general_ci,COERCIBLE) for operation '='src/XF/Db/AbstractStatement.php:230

Thanks!

Edit:
I found @AndyB...

Read more
Preventing -Redacted- characters in username

free plugins
minecraft paid for free
mcmarket
mc-market
free minecraft paid plugins
free minecraft plugins
spigotmc
SpigotMC
aac free
ewg free
Minecraft Premium Plugins
ewg free download
litebans free
epicworldgenerator free
free schematics
leaked schematics minecraft
schematics
schematics leaked
schematics free
minecraft schematics free
paid minecraft schematics free
paid minecraft schematics for free
free cracked plugins
free cracked minecraft plugins
plugins
featherboard download
featherboard plugin download
antiaura download
xenforo leaked
xenforo for free
xenforo addons