My washing machine drain is over flowing.
There is a plug below the floor drain. This is why when the washer drains it backs up. Soon it will start backing up when you take a bath.
The reason it got worse is the land lord knocked more debris into the plug and it is draining even more slowly.
A long power snake is the best way to clean these problems as it will get worse with time, drain cleaner may help but I wouldn’t count on it. (I say it will start backing up with a bath, this depends if the bath is on the right side of the plug).