I assume this is because some ATK role or something needs to be done in orca,
i leave this here to track this issue.
https://mail.gnome.org/archives/orca-list/2019-March/msg00094.html
Reproduce:
Open Plasma 5.15
Start orca
open multible windows
press alt + Tab to switch windows
expected result:
Same as in gnome - Interrupt, speak new entry
current result:
no interruption when entry is changed.