Does this affect queries and updates identically?
DTS will not apply to queries and queries will keep the existing limit.
The main motivation for having an instruction limit for queries is to bound the resource consumption. That’s because queries run concurrently to update messages and do not block the progress of IC. Each query keeps a reference to the corresponding replicated state when the query started. If we allow long-running queries, then we may get into a situation where IC has executed many rounds while the query is still running and keeping a very old state in memory. (This is a similar concern that block inter-canister query calls: Inter-Canister Query Calls (Status: done) - #44 by akhilesh.singhania)