I was trying API,
https://addons.mozilla.org/api/v5/....
with some syntax error at the beginning, and was debugging with curl. Tried for maybe 20 times.
Then suddenly got banned for 1 hr.
Next day, continued debugging. Tried for maybe 10 times. Then got banned for 3 hrs. 
{"detail":"Request was throttled. Expected available in 11595 seconds."}
Although API server firewall protection is good, is is too sensitive?