There's an earlier post, here on SN, that addresses this fairly comprehensively:

How does Bitcoin protect itself from Core Developer corruption and misinformation campaigns?

bitcoin

How Bitcoin updates are made? who makes the decision, miners and node holders? whales with nodes?

thedevil4k

There's an earlier post, here on SN, that addresses this fairly comprehensively:

*How does Bitcoin protect itself from Core Developer corruption and misinformation campaigns?*
https://stacker.news/items/31891