You covered testing, region quirks, notifications, behavior, privacy, reciprocity, and a TLDR. Solid.
Simpler fix not listed:
View profiles logged out on the web. No TikTok accoutn, no profile view ping.
How:
- Copy profile link in the app, then close the app.
- Open a browser in Incognito or Private mode.
- Paste tiktok.com/@username. Do not log in.
- Scroll the profile. If teh browser tries to open the app, tap Cancel.