Hi. I've solved this one, but thought I'd post about it in case someone else has the same problem, and also in case I can learn more on this topic.
After upgrading to Ventura yesterday none of my Safari macros were working. The solution was to go to my Safari macro group and remove then re-add Safari in the "Available in these applications" list.
All other macros I've tried worked without this fix—so far the problem was just with Safari.
Discovered the same thing 30 min ago. Easy fix as you described. Now trying to figure out why the Stream Deck Set Image action stopped working with Ventura. 
Not to derail this topic, but I found that if I gave the Stream Deck app Full Disk Access in System Settings --> Privacy & Security the Stream Deck Set Image action started working.
I've run into the same issue and… it keeps coming back. The list of Safaris is growing.
Anyone with how to resolve permanently (or maybe a Global Macro to re-add Safari 
)?
Have you been removing Safari before re-adding it? It looks like you've just been adding new Safaris?
@ccstone Thanks for the tip about Onyx, which I just ran. I'll update if issue does not present after a couple of weeks, or earlier if it does.
@Richard_Tench I used to remove Safari before re-adding it, but it didn't matter either way. My guess is KM identifies each app not by name but by a UUID and so each add referenced (from KM's perspective) a new app.
This issue happens on at least two of my machines. I'll add more details if they become relevant.
Thanks both!
Don't leave a bunch of non-functional associations in the macro group...
Have you played with the available options?
@ccstone Cleaned up per your recommendation.
Thanks for tip on matching options. I'll experiment if issue represents.
Used Onyx on 6 Feb. Cannot recall if I changed from "Match by Default" to "Match by Path".
Issue presented again a couple of days ago (23 Feb).
I then
I'll follow up in 2 weeks or so.
I would recommend using "Match by Bundle ID". That has worked for me with this Safari/Ventura issue.
I set it up like this weeks ago and it hasn't caused problems since.
Thanks @Zabobon for the tip for those of us on Ventura. I'm following your guidance.
Will update in a couple weeks or if issue represents.
Following up: since following @Zabobon's suggestion to use "Match by Bundle ID" my Safari-targeted Keyboard Maestro macros work as expected.
Thanks again, all, for your helpful suggestions.
After upgrading to Sonoma, Safari would not execute any macros, even though Safari was enabled for the macro group. When clicking "Safari" under the "Available in these applications" list, I noticed there were TWO Safari icons. The checked one appeared to be a Safari alias icon (with the small black arrow in its corner). I checked the other Safari icon instead, and now the macros are executing in Safari.
Just documenting this in case it helps someone else.
{I realize this thread is about Ventura, but it's practically the identical issue.}