WhatsApp for Oppo Reno 13

ColorOS aggressively limits background apps to save battery, which delays WhatsApp messages until you open the app. Go to Settings > Battery > App battery management (or Power consumption protection) > WhatsApp and turn on Allow background activity and Allow auto launch. Then open Settings > Apps > WhatsApp > Notifications and make sure notifications and all channels are enabled. Finally, open the Recent Apps screen, pull down on WhatsApp's card and tap the lock icon so ColorOS stops clearing it from memory. See how others solved this on Reddit

The full-screen incoming-call UI fails to appear when ColorOS blocks WhatsApp's background and display permissions. Go to Settings > Apps > WhatsApp > Permissions and enable Display over other apps (Display pop-up windows), then go to Settings > Notification & status bar > Manage notifications > WhatsApp and turn on Lock screen notifications and the Calls channel. Also set Settings > Battery > App battery management > WhatsApp to Allow background activity (don't optimize/restrict it) so the call screen can fire while the phone is locked. See how others solved this on Reddit

This sorting glitch usually clears after a full restart and after confirming WhatsApp is fully updated from the Play Store. If it persists, clear WhatsApp's cache via Settings > Apps > WhatsApp > Storage usage > Clear cache (this does not delete your chats), then force-stop and reopen the app. If only one or two threads are stuck, archiving and unarchiving that chat often forces the list to re-sort. See how others solved this on Reddit

Heavy drain usually comes from constant background syncing plus auto-downloading media. In WhatsApp go to Settings > Storage and data > Media auto-download and set the options to Wi-Fi only or No media so it isn't downloading in the background on mobile data. Then in ColorOS go to Settings > Battery > App battery management > WhatsApp and turn on Optimize background power usage (instead of Allow background activity) so it still receives messages but isn't allowed to run unrestricted. See how others solved this on Reddit

Video-call freezes and a blank screen are usually caused by the proximity sensor or by ColorOS throttling the app under background restrictions. In Settings > Apps > WhatsApp > Permissions make sure Camera and Microphone are granted, and set the app to Allow background activity under Settings > Battery > App battery management. If the screen blanks mid-call, clean the area around the front camera/earpiece where the proximity sensor sits, and turn off any screen-recording or game-mode overlays before calling. See how others solved this on Reddit

Common first-week complaints are delayed app notifications, occasional UI lag, and bloatware running in the background. Start by installing all pending updates via Settings > Software update, then disable or uninstall unused preloaded apps and turn off battery restrictions for WhatsApp and your other key apps under Settings > Battery > App battery management. A one-time restart after updating settles most of the early ColorOS quirks. See how others solved this on Reddit