One of the test cases in jstests/core/timeseries/ddl/timeseries_collection_uuid.js is to check that for legacy timeseries collections, trying to e.g. insert a measurement using the UUID of the system.buckets collection, will fail with a CollectionUUIDMismatch error.

> db.createCollection("ts", {timeseries: {timeField: 't'}})
> db.getCollectionInfos({name: "system.buckets.ts"})[0].info.uuid
> db.runCommand({insert: "ts", documents: [{t: ISODate()}, collectionUUID: bucketUUID})
[...] time-series insert failed: test.ts :: caused by :: Collection UUID does not match that specified[...]

This tests case can be removed once 9.0 becomes last LTS.