Data loss with overflowed SVG2 text

Steps to reproduce:

• open Inkscape
• create a flowed text (text tool: click and drag)
• type text, so that the text box overflows
• save the file
• close Inkscape
• open the file again
• drag the handle of the flowed text box to increase its size

What happened?

• the text that didn't fit the box is missing, it is also missing when opening the file in a text editor
• the text doesn't reflow (probably due to the <svg:tspan> elements)

What should have happened?

• all text is still there
• the text reflows

Inkscape Version and Operating System:

• Inkscape Version: 1.1-dev (03ae7f7a, 2020-01-04)
• Operating System: Windows 10
• Operating System version: 10.0.18362