Hello Everyone
This filter plugins conflicts with simple certificate plugin,  it's uses the same text tags format,  {...}, so conflicts is inevitable.

And the tag {username}  is conflicting,  since in simple certificate plugin means full user name,
and in this plugin is the user login

I suggests to change the plugin text tags to something like [username] or (username) or  \username\ or username or  anything besides { ... }, since simple certificate is an older pluging and more popular too (of course it is, it's more older ...  )