The bot prints 'No tokens found!' and exits immediately because TOKENS resolved to nothing.
load_dotenv() reads .env relative to your current working directory, not the folder mizu.py lives in. If you launch from a different folder, or a parent that has an empty .env, TOKENS resolves to nothing. Also triggers if .env is missing, the TOKENS= key is absent, or the value is empty.
Run the bot from inside the owomizu/ folder: cd owomizu && python mizu.py. Confirm owomizu/.env contains a non-empty TOKENS= line. Recent builds pin .env to mizu.py's own folder via an absolute path, so cwd no longer matters after updating.
TOKENS=TOKENS="token1 channel_id1;token2 channel_id2"