expensive Twitter/X API prices

We have two WordPress plugins to automatically post updates to X and to Mastodon.
The X (formerly Twitter) plugin wanted an updates API token to work with the new V2 X API.

Doing that we found out that we have been automatically set into the „Basic“ developer account for 100USD/Month instead of the „Free“ account.
Luckily we detected this move by X before the first invoice.