After installing Continuity's alpha version for 1.19.3 (and enabling its default connected texture resourcepack) SSPB stops working.
This issue can be worked around by setting ambient-occlusion-mode to hybrid in the indium configuration.

This bug can be reproduced with Continuity, Fabric API, Indium, Sodium and SSPB.
Download link for Continuity alpha 1.19.3

Additional info provided by Continuity's author:

Yes, this is the same incompatibility with LambdaBetterGrass that was mentioned on CF and Modrinth. I suppose I should have just been more general and said that it was an Indium rendering incompatibility, rather than just saying it was incompatible with a single mod.

I've thought about adding a new feature that would also address this, but for now, just keep using hybrid mode.