How to solve: SimCity BuildIt crashes during startup on an old Android phone.

SimCity crashes during startup on Xiaomi Pro 7 (EOL; 6GB RAM, Android 10).
Reinstalling, factory reset, or reflashing to an Android 9 ROM does not help.

Root cause: Too many buildings in the "Capital City" at startup (possibly due to buffer/registry/memory mismatch?).
Tip: Always move to "Frosty Fjords" (a smaller area with fewer buildings) before exiting the game. This way, SimCity will start without crashing next time. Once the game has started, you can switch to other cities without problem.

NB: If your city is on an older smartphone and you don't connect the city to Google/Facebook, you may need to transfer the SimCity ID (the file "ids") to a newer device to get it launch. 

The file is located in:
/Android/data/com.ea.game.simcitymobile_row/files

Note: From Android 12 and above, the /Android/data folder is restricted. You’ll need to use Shizuku (look it up on Google) to access it via ADB. Good luck.