The endless fluff and clutter to clean up (Search bar appearing on desktop, sidebar foistware). The relentless marketing and push of adjacent services (Bing AI).
The passive-aggressive IE compatibility mode (unremovable nag banner to stop using IECM, your Legacy App URLs expire after 30 days for no good reason).
It's a thin wrapper around Blink just like Chrome/Chromium. What is there to "hate"?