A few instructors are teaching a weird mish-mash of tai chi and some other art, such as karate.
These classes are pitched as being innovative, realistic, pragmatic.
Yet, mixing tai chi and external practices together does not improve the quality of the tai chi.
Rather, it diminishes the value of the tai chi component.
The instructor is demonstrating their inability to understand and apply tai chi using the tai chi principles.
They have opted for a short-cut, and are filling-in the holes in their knowledge using concepts and approaches from other martial arts.
There is nothing wrong with developing your own art if that is your desire, but you should not call it 'tai chi'.