Vivo U10 Custom Rom Link

explicitly states they do not provide unlocking tools and that rooting voids the warranty. Unofficial Workarounds

Most likely, yes. Unlocking the bootloader often degrades Widevine from L1 to L3, limiting Netflix to SD quality. vivo u10 custom rom

Since the vivo U10 is a budget device with proprietary hardware, some features may not work perfectly on Custom ROMs. Common bugs reported by users include: explicitly states they do not provide unlocking tools