There are two consequences of this:
1) The chair damages the mat, so occasionally I have to replace it.
2) The mat damages the carpet, because it has spikes underneath it to stop it from slipping.
Following 1), I recently ordered a new mat from Amazon. Leaving aside the vast amount of packaging it came in, this is what it looked like:
On top of it are some blue gloves. The instructions told me that the gloves should be worn to unroll the mat, because of the spikes.
That's thoughtful. What was less thoughtful was the fact that the gloves were stuffed inside the mat, so I had to unroll it to get them. It would also have been handy if the instructions telling me to wear the gloves weren't themselves with the gloves.
Now, I merely have to flatten it by weighing down the corners and leaving it in direct sunlight for three hours.
We're sure to be getting another heatwave soon, I'll do it then.