Poor Apple Watch battery life after iPhone 6 to iPhone 8 upgrade

I’ve been searching on the internet and going through Apple forums but couldn’t find any info.

After upgrading my my iPhone from an iPhone 6 to an iPhone 8 my battery life on my Apple series 0 Watch has reduced by at least 30%. I used to easily be able to wake up at 7am and if I forgot to charge it when I went to bed, I would usually last until mid-afternoon the next day.

Yesterday, I took my battery off charge at about 1pm and by 9pm I was on 48% charge. Well below what I’d normally expect.

I obviously re-paired the Watch with the new iPhone 8 and didn’t change any settings after re-pairing. Does anybody know if there any new defaults the iPhone 8 could have set, or has anybody experienced this? I’ve had the new phone and watch pairing going for a week now so it doesn’t seem to be a one off Event.