The HTTP status of 429 means “Too many requests.”
As explained here, the HTTP status code means too many requests are being made:
The user has sent too many requests in a given amount of time ("rate limiting").
Then checking usage limits on Google Sheets in the official Google guide states:
This version of the Google Sheets API has a limit of 500 requests per 100 seconds per project, and 100 requests per 100 seconds per user. Limits for reads and writes are tracked separately. There is no daily usage limit.
To view or change usage limits for your project, or to request an increase to your quota, do the following:
- If you don't already have a billing account for your project, then create one.
- Visit the Enabled APIs page of the API library in the API Console, and select an API from the list.
- To view and change quota-related settings, select Quotas. To view usage statistics, select Usage.
So your choice seems to be is to increase the limits via upgrading your account. Or—depending on usage—you can limit interactions on your sheet in your application by only requesting data remotely when needed.
This all depends on your project, but many APIs have limits like this and the best/simplest way around them is to store the data locally in your app—or a custom API—so you cache the data locally and interact with the data locally and then only refresh from the API at predetermined intervals/methods that would avoid triggering 429 error.