After finding some issues in 1.13.0, we halted the phased roll-out of 1.13.0 and focused on getting a quick bugfix update completed: 1.13.1. This time around, we're doing a standard release, so all users should now have access to a 1.13.1 update, regardless of whether they were on 1.12.3 or 1.13.0 previously. Please let us know if you have any questions about how the rollout is working!
A major known issue still in 1.13.1 is some performance degradation in Lua that many devs pointed out upon updating to 1.13.0. We're aware of that and are working on a fix that we hope to release soon.
Also, please note that the version number shown on Develop for Playdate might still be 1.13.0 for a short time, due to a server hiccup. However, if you download the SDK installer as of now, you should still receive version 1.13.1. (Please let us know if you don't!)
Please check Playdate SDK Changelog for additional details on the release.