Caught this issue today due to a failing workflow - for reference this workflow has been running daily since June 2023 without this failure, so my assumption is that something just changed.
The REST API endpoint /rest/api/3/worklog/updated provides a nextPage URL for the next set of updated worklogs. As of writing this, both in the REST API documentation (link) & actual use, the nextPage URL returned on a successful request has the following format: rest/api/3/worklogupdated?since=...

I am not sure if this is a recent change, or if this is how the nextPage URL has always been, but if this nextPage URL is used as-is now, the result is a 404 error.

In order to fix this, we are replacing worklogupdated with worklog/updated in the above returned URL.
This is not expected behavior given the REST API documentation. Just wanted to make others aware.