OP you must be new. This is a well known issue since mid late 2018. Please search, and either fix it yourself if so inclined or get the replacement parts from the Service Centers parts dept.
Most, have them in stock.
Front, center and rear splash guards/shields, as required.
If its the front one (doesnt seem to be) you can also replace with the Model Y injection molded plastic equivalent.
And if its the center rear... do yourself a favor and make a few holes in the rear plastic splash guard/diffuser to help drain off water before it meets the material.
Threads on that on here, other fora and the interwebz in general as well.