GitHub is going all in on the copyright-for-thee-but-not-for-me hallucination-as-a-service planetary-scale-incineration-scheme AI bullshit bandwagon with its GitHub Copilot crapware, showing it everywhere on github.com, and unfortunately it's sometimes impossible to disable it:
If you have been granted a free subscription to GitHub Copilot Individual as a verified student, teacher, or maintainer of a popular open source project, you will not be able to cancel your subscription.
Fortunately, it's trivial to hide it with those rules for your favourite ad blocker:
github.com###blob-view-header-copilot-icon
github.com###copilot-floating-button
github.com##li.ActionListItem>a[href="/copilot"]
github.com##li>a[href="/github-copilot/signup"]
github.com##div>button#copilot-md-menu-anchor-new_comment_field
github.com##div#copilot-button-container
github.com##react-partial[partial-name="copilot-code-chat"]
github.com##li.ActionList-sectionDivider:has(h3:has-text(Copilot))
github.com##div.AppHeader-CopilotChat
github.com##.copilotPreview__container
github.com###copilot-md-menu-anchor-pull_request_body
github.com##div[data-test-id=copilot-actions-chat-button]
github.com##div:has( > button#diff-lines-copilot-button)
And while you're at it, add github.com##aside.feed-right-sidebar as well to
remove the useless right side-bar.