Yes your carpets can shrink when cleaned
Carpets shrink because of the operators lack of understanding
Solution at too high pressure can be forced down using hot water extraction processes straight to the backing, this is where shrinkage happens depending on the construction.
It is easy to believe that wool carpets shrink more than synthetic but actually it is the other way around.
It is the swelling of the fibres in the construction that causes shrinkage, not the face fibre.
Wool carpets are highly absorbent and won't allow as much water to pass to the backing where as a synthetic carpet will allow moisture to pass into the backing, so we can begin to understand why it is important that the operator knows what they're dealing with to avoid any damage.
If the carpet is not adequately secured, this can also bring problems.
A simple inspection by a professional carpet cleaner will determine the safest cleaning method to ensure no shrinkage