Google will be deprecating the Google My Business API on April 30, 2022 and replacing it with new APIs in the Google federated model. So you will have to update any of the old APIs you may be using with the new ones within the next few months.
Mike Blumenthal, a local SEO, posted the PSA on Twitter saying "PSA: If you have been using the GMB api it is being replaced by a federated, more granular set of APIs, each for a specific function."
You can see the deprecation schedule over here that shows all of the Google My Business APIs sunsetting on April 30th. Google said the existing endpoints will be deprecated and eventually sunset. The deprecated indicates that the version of the API will continue to function as expected, but may not be updated with new features or bug fixes. However, support will be limited, Google said. The sunset indicates that the version of the API is removed and no longer available.
Here is the table, copied from Google:
| Deprecated Resource | Replacement Resource | Deprecation date | Sunset date |
|---|---|---|---|
| accounts.locations.questions [Google My Business API v4.9] |
locations.questions [Questions API v1] |
2021-11-18 | 2022-04-30 |
| accounts.locations.questions.answers [Google My Business API v4.9] |
locations.questions.answers [Answers API v1] |
2021-11-18 | 2022-04-30 |
| accounts [Google My Business API v4.9] |
accounts [Account Management API v1] accounts [Notifications API v1] |
2021-02-22 | 2022-04-30 |
| accounts.admins [Google My Business API v4.9] | accounts.admins [Account Management API v1] | 2021-02-22 | 2022-04-30 |
| accounts.invitations [Google My Business API v4.9] | accounts.invitations [Account Management API v1] | 2021-02-22 | 2022-04-30 |
| accounts.locations.admins [Google My Business API v4.9] | locations.admins [Account Management API v1] | 2021-02-22 | 2022-04-30 |
| accounts.locations [Google My Business API v4.9] | accounts.locations [Business Information API v1] locations [Business Information API v1] locations [Verifications API v1] | 2021-08-24 | 2022-04-30 |
| attributes [Google My Business API v4.9] | attributes [Business Information API v1] | 2021-08-24 | 2022-04-30 |
| categories [Google My Business API v4.9] | categories [Business Information API v1] | 2021-08-24 | 2022-04-30 |
| chains [Google My Business API v4.9] | chains [Business Information API v1] | 2021-08-24 | 2022-04-30 |
| googleLocations [Google My Business API v4.9] | googleLocations [Business Information API v1] | 2021-08-24 | 2022-04-30 |
| attributes [Google My Business API v4.9] | locations.attributes [Business Information API v1] | 2021-08-24 | 2022-04-30 |
| accounts.locations.verifications [Google My Business API v4.9] | locations.verifications [Verifications API v1] | 2021-08-24 | 2022-04-30 |
Forum discussion at Twitter.
