The term filter is a terrible implementation of blocking RMT spam

[Exmo]

even if op's problem has been solved, it's still a terrible implementation because the filter is case sensitive of all things and requires a minimum character limit.

to say nothing of how people go to lengths such as this with those block letters to bypass filters.

The filter should not be case sensitive. But this example looks like it was intentionally constructed to bypass the term filter. The devs could update it to treat block letters as their ascii version and still some people would find a way around it.