I have seen this when approaching ~30% context window remaining.

There was a big bug in the Voice MCP I was using that it would just talk to itself back and forth too.

Same.

I'll have it create a handoff document well before it hits 50% and it seems to help.

Most of our team has moved to cursor or codex since the March downgrade (https://github.com/anthropics/claude-code/issues/42796)