This is a result of a number of factors more than likely. Root cause is a bad detergent/soap to water ratio, which can be caused by putting too much in or unexpectedly soft water (people who are used to putting hard-water amounts of soap into washing machine loads who suddenly move somewhere with super soft water will often do this once or twice before dialing it back), but a contributing factor here is likely that the drain line that the hose is dumping into is partially clogged, so the suds are having a chance to backflow up past the hose instead of staying with the flow of the water, or the wrong type of soap is used as was mentioned above.
What’s happening here?
This is a result of a number of factors more than likely. Root cause is a bad detergent/soap to water ratio, which can be caused by putting too much in or unexpectedly soft water (people who are used to putting hard-water amounts of soap into washing machine loads who suddenly move somewhere with super soft water will often do this once or twice before dialing it back), but a contributing factor here is likely that the drain line that the hose is dumping into is partially clogged, so the suds are having a chance to backflow up past the hose instead of staying with the flow of the water, or the wrong type of soap is used as was mentioned above.