Changing line height in flowed text: When switching to another tool with the selection still active, line height is applied to the entire text

Steps to reproduce:

Please see the attach video

Step to reproduce:

1. create a flow box
2. Give global line space
3. Give some individual lines some different space
4. now go to any other tool (edit by @jhofinger: without deselecting the selected lines)
5. The different line space will become global line space
6. Pressing undo sort things out.
7. Exception shown in video (attached)

Inkscape Version and Operating System:

1.1-dev (1a7f71c, 2020-04-24) Debain 10 sid

tut1