The reference guide has not been updated since 7/27/21, and still says that a Subtitle track can export STL sidecar. But as of PR 22.1.2 or earlier (I assume 22.0), there is no longer an STL export in the Export -> Media or Export -> Captions windows - and it is also absent in the latest Beta.
I tested PR 2021.4.0 - STL export was present.
I tested the lastest Beta for what SRT sidecar is exporting with the styling option selected. I added 4 edits: font color, font family, background yes/color, and location. The only information in the SRT export is font color.
Steps to reproduce: 1. Create sequence with Subtitle track. Export using Export -> Media or File -> Export -> Captions. Result: The only sidecar option is SRT. Expected: STL would also be available.
System info Application: Premiere Pro (Beta) v220.127.116.11 OS: Windows v10.0.19043, RAM: 63.80 GB GB, CPUs (logical): 16