Something I used in my previous life as a product manager.

Note: This is from before I knew anything about accessibility, so does not explicitly cover accessibility issues.

Priority 1 - Highest (Urgent)

These are 'launchblockers', or even in some cases 'someone needs to wake up right now'

Security, privacy, or life-altering information is compromised
- Security cert or encryption fails
- User is shown or able to access another user’s information
- Incorrect information or advice shown which could be life-altering (financial, health, legal, etc)
- Legal or regulatory risk (for example, GDPR non-compliance)
App is completely inaccessible or unusable
- Browser crashes or freezes
- Page is blank or inaccessible
- UI elements broken such that it renders the page on usable

Priority 2 - High

Functionality is broken such that user cannot proceed or cannot perform a core action:
- Unresponsive UI elements
- Infinite or unreasonably long page loading time
- Broken links
- Error message that is unresolvable by the user

Functionality technically works but usability is severely affected:
- UI elements distorted or mispositioned making them hard to access or interact with
- Visual or textual elements are not intuitive, potentially inhibits uses understanding of feature

Core design elements are incorrectly implemented:
- Brand colours
- Typography
- UI components (buttons, selection components)
Design details that affect polish or slickness of the products, but do not impact usability:
- Minor inconsistencies in size or positioning of UI elements
- Design or wording is inconsistent with other parts of the app
- Animation or interaction is missing or incorrect