The default data source, for data made by scripts, is now "Seita".

This is not what users want, of course. It should be "FlexMeasures" per default, and ideally a config setting, which can easily be set to the name of the Energy Service Company (ESCo) running FlexMeasures.

Issue #506 is of interest here, too. But their implementation should not interfere, I expect.

As for migrating existing data, I'm not sure we have a good solution. Usually, I'd expect existing users also to use their own company name as source. And for our own data, we'd like to keep "Seita", actually. I'd mention in the release notes that people might want to run an update statement, should they want to rename. Probably on the data source itself.