I had this problem recently and I resolved it by going to the highway where I floored it. I had no dashboard alarms or anything. Currently I subject my nice Skoda to short low rpm city trips which all in all is less favorable for the engine system. That is the root cause of the problem. Because I was curious (wanted to see if my deduction were correct) I submitted the following search string in google: "2019 skoda octavia 2.0 tsi 190hp combi : Very bad fuel economy until I took it to the highway and floored it. What could the reason be?" The google search confirmed in total what had happened and what I had experienced. So I will be brief and advice you do the google search and read the response. Next time if the problem reemerges I might try to put the DSG into manual and run the engine at high rpms but at lower speed on the highway, a little like what I sometimes did with my old 2005 Octavia with the 2.0 turbo diesel engine before I went to the emission tests. Hope this helps in case you have a 2019 skoda octavia 2.0 tsi 190hp combi or similar, which suddenly starts drinking fuel fast with no obvious reason.