Besides paper notes and brainstorming with my own self on my whiteboard, I sometimes disconnect from the vpn and put myself offline in MSTeams for several hours, telling my manager and direct teammates that they can use pagerduty to ping me if urgency calls for my immediate availability, when wanting to focus on a specific task/piece of code/resesrch/document/architecture decision.

Context switches can really kill productivity. So much that sometimes I do much more work in a 2h window between 7am and 9am than the next 6-7 hours.