That was the integration into the Swiss train schedule.
They improved the line (electrification which allows better trains, moving tran station in Lindau from the island with old town to the shore etc.) in the first year they went from 4h30 to 4h. Where the trains were standing for about half an hour at St. Magrethen at the Austrian-Swiss border. In 2021 they improved signalling and adjusted schedules and got rid of that half an hour wait, so it's now at 3h35.
They improved the line (electrification which allows better trains, moving tran station in Lindau from the island with old town to the shore etc.) in the first year they went from 4h30 to 4h. Where the trains were standing for about half an hour at St. Magrethen at the Austrian-Swiss border. In 2021 they improved signalling and adjusted schedules and got rid of that half an hour wait, so it's now at 3h35.