I did the same, but did it on Debian Testing. Big mistake. KDE is not well supported on Debian. I too have seen the light in the Void and migrated about a month ago; better experience all around, including a modern KDE.
KDE runs very smoothly on Debian stable. Had it running on testing also, but sid/testing can break from time to time...
I switched from GNOME to KDE on Debian testing and it has been going great so far. What issues were you seeing back then?
I had the exact opposite experience. I starting using KDE 5 for both work and personal use about 6 months before bookworm became stable and have been extremely happy with it ever since. And I say this as someone who is typically very critical of the roughshod nature of Linux desktop environments. (Namely: every time we have something good, a person or team comes along and wants to rewrite it in their image. Hopefully the KDE devs can stay the course this time and adhere to evolutionary rather than revolutionary growth.)