iphone 12 pro batt health drops to 95 % in a few days ...less than 8 months old....apple support useless .... last iphone i will ever buy and ive had them all .... none has ever deteriorated this fast ....apple support useless

If the phone is 8 months old 95% is in the normal range. Batteries are consumables; they lose a little capacity every time they are discharged, then recharged. On average this works out to about a 1% loss for every 25 “full charge cycles” ( some will be a little more, others a little less). As one example, if you charge the phone overnight, every night (and that is what you should do; it is a best practice), it starts the day at 100%. If it drops to 20% by the end of the day before you charge it again overnight that counts as 0.8 full charge cycles (20% to 100%), or about 24 full charge cycles per month of use. For this example your battery capacity will lose about 1% per month. Of course, if the end-of-day level is higher than 20% the capacity loss will be a little less, and if it is lower than 20%, or you charge it during the day, the capacity loss will be higher.

The absolute best way to improve the life of your battery long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight, every night. The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern. If you enable iCloud Backup (Settings/[your name]/iCloud - iCloud Backup) the phone will back up overnight also, assuring that you can never lose more than the current day’s updates.

I'm not sure what the issue is here. iPhone batteries are rated to reach 80% battery capacity after 500 charge cycles. For most people, 500 cycles comes around 2 years into their iPhone's life. With some basic math, one can extrapolate that it would take 32 months total for your iPhone's battery to become significantly deteriorated (below 80%), which is longer than the expected 24 months.

My advice is to use your iPhone as your normally would and stress less about the battery health of your device.