That is because the floor isn’t chroma green. In fact, it is mathematically closer to yellow than to green. Green hue=120. Yellow hue=60. That floor is around hue=80-85.
You have 2 options….
1. Reduce the min hue value in the EZ Green Screen setting. Try going all the way to 70 which is as low as you can set it. That should remove most of it. However, there are probably speckled areas in it that go below 70 hue and those areas would not be fully removed.
2. Or you can try the remove floor actions. See the video in this link. You don’t need to change the settings for this. However, this relies on select subject to cut out around the feet. If select subject selects the mat then it won’t erase it.