Delayed on notifications some silent

Hello i am using techno spark 8 my problem is my chime alarm reminder its delaying some notifications the go silent can you please help me what will be a problem because i did everything switch off battery optimization i also put the app on auto start but still i am getting problems.

Unfortunately I can’t can’t make this app work exactly on time on some device (like VIVO, yours might be among them) due to too aggressive battery optimizations that can’t be turned off. Even when theoretically all optimizations are turned off it still doesn’t work.