As of watchOS 9, Apple has deprecated a large portion of the CLKComplication* API in favor of migrating to WidgetKit.
The number of supported complication families has been reduced.

At least one of of Loop's existing complications (stack text on the X-Large face) is reportedly no longer working on watchOS 9 as Apple appears to only support circular complications on that face now:
The Extra Large watch face has long been a great way for people to see the time in an extra large format. And it supports a single, large circular complication. - WWDC22: "Go further with Complications in WidgetKit" @ ~ 5m 45s
I experimented with a new WidgetKit based complication extension on a Loop fork here but am running into roadblocks accessing LoopDataManager to build timeline entries and am unable to spend much more time on this at the moment.
As of watchOS 9, Apple has deprecated a large portion of the
CLKComplication*API in favor of migrating to WidgetKit.The number of supported complication families has been reduced.
At least one of of Loop's existing complications (stack text on the X-Large face) is reportedly no longer working on watchOS 9 as Apple appears to only support circular complications on that face now:
I experimented with a new WidgetKit based complication extension on a Loop fork here but am running into roadblocks accessing
LoopDataManagerto build timeline entries and am unable to spend much more time on this at the moment.