Currently, the imgur API keys has limited rate for month, if users of flameshot keep growing, the limit could be reached. How to handle rate limits?
imgur API

Rate Limits
The Imgur API uses a credit allocation system to ensure fair distribution of capacity. Each application can allow approximately 1,250 uploads per day or approximately 12,500 requests per day. If the daily limit is hit five times in a month, then the app will be blocked for the rest of the month. The remaining credit limit will be shown with each requests response in the X-RateLimit-ClientRemaining HTTP header.

We also limit each user (via their IP Address) for each application, this is to ensure that no single user is able to spam an application. This limit will simply stop the user from requesting more data for an hour. We recommend that each application takes precautions against spamming by implementing rate limiting on their own applications. Each response will also include the remaining credits for each user in the X-RateLimit-UserLimit HTTP header.