Does activation just mean a node is running 0.21.1 or do they have to take extra steps after the the upgrade to 0.21.1?
Put simply...
Either:
- Miners activate the fork. This happens when a certain % of miners are making blocks with a special "taproot ready" flag embedded in their mined blocks. This % of blocks must continue for ~2 weeks (for 2016 blocks)
- Users activate the fork. This happens when the timeframe for activating the fork expires
It's a little more complicated than though. Not much.
As of yet, the % for triggering the 2016 block lock-in stage hasn't been decided. Suggested figures are 90% or 95% of blocks (95% was used for some recent fork activations). The overall timeframe is also not exactly decided, but 1 year (measured in blocks...) seems to be a popular suggestion.