The launcher does not update the lastUsed attribute in the launcher_profiles.json file, so the default profile is not the previously used profile.
Steps to reproduce:
Select a profile that is not selected by default.
Load up Minecraft.
Quit Minecraft.
Re-open the launcher.
The default profile will not be the profile that you previous launched.
Thank you for your report!
We're actually already tracking this issue in MCL-12104, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki