From the scientific article's[1] own plain-language summary: "The Thwaites Eastern Ice Shelf is the floating terminus of the Thwaites Glacier, one of the fastest changing glaciers in Antarctica and contributing as much as 4% of global sea level rise today. This floating ice shelf is stabilized offshore by a marine shoal and acts as a dam to slow the flow of ice off the continent into the ocean. If this floating ice shelf breaks apart, the Thwaites Glacier will accelerate and its contribution to sea level rise will increase by as much as 25%."
So, this specific ice shelf's collapse would increase global sea level rise by up to 1%. Over the coming decades, the dominant driver of sea level rise will continue to be thermal expansion of the ocean itself. The West Antarctic Ice Sheet in total may contribute 3 m of sea level rise... over a period of 13 thousand years[2].
[1]: https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/978762