SUMMARY
If I add an attachment, redrawing of the window becomes sluggish. When I type text, the status bar is updated, but the text does not appear in the window, unless I move the mouse pointer to another part of the window outside the message text area. It is interesting that this happens only when I add an attachment; opening a message with an existing attachment does not demonstrate this.

STEPS TO REPRODUCE
1. Create a new email.
2. Add an attachment.
3. Attempt to resize the attachment pane or type text.

OBSERVED RESULT
Redrawing is very sluggish. Typing text does not update the display.

EXPECTED RESULT
The display should be updated normally.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSUSE Tumbleweed
KDE Plasma Version: 5.25.3
KDE Frameworks Version: 5.96.0
Qt Version: 5.15.5

ADDITIONAL INFORMATION
On Wayland.