What's the difference between Timescale's license ("free to everyone except cloud providers") and GPLv3?
The differences are pretty substantial. The GPL puts no restrictions whatsoever on how you can use software that falls under it. Timescale's license, on the other hand, gives you very limited usage rights. You can use unmodified versions of the software, but you can't allow clients to make schema changes, nor can you use it to provide any service that is "primarily [a] database storage or operations product or servic…
I mean, to be fair and add some balance here, a lot of people find that part of the GPL to be very restrictive.
There are many organisations who have banned the use of GPL code altogether because of this, and also because of ambiguity in the license (e.g. the never ending debate about static and dynamic linking etc).