It is a hydrolysis that proceeds by a nucleophilic substitution of chloride by hydroxide followed by elimination of HCl.
The substitution step is loss of chloride from 2-dichloromethylphenoxide, followed by addition of hydroxide. This is, as far as I can see, an SN1 reaction, the product of which eliminates HCl spontaneously.
SN1 and hydrolysis are not mutually exclusive terms. Hydrolysis is a term referring to the overall result of the reaction - a comparison of input to output - while SN1 is descriptive of the mechanism - how the output is generated from the input.
I would say it is a hydrolysis reaction that involves an SN1 substitution step (in addition to an elimination step).