If your active, Autolaunched Trigger Flow was last modified before Summer ’21 (around May-June 2021), it won’t show up in your Flow Trigger Explorer.
Thanks to Jack O’Brien for finding the relevant help article!

oh yah. . . you can translate a number like “232” into a seasonal Salesforce release by modifying the 248 in the following URL and seeing which release’s notes pop up:
. . . Salesforce increments each seasonal release by 2, and counting back from Spring ’24 (internally numbered 248) gets us. . .
- 246 = Winter ’23
- 244 = Summer ’23
- 242 = Spring ’23
- 240 = Winter ’22
- 238 = Summer ’22
- 236 = Spring ’22
- 234 = Winter ’21
- 232 = Summer ’21
so there ya go! Looks like that URL-hacking trick works all the way back to 218 (Spring ’19).