i dont think thats because of the august update, the phone's battery is wearing out and it might need a replacement. all batteries wear out eventually, after long term use (theres already a difference in a year or 8 or so months) which lead to battery life decreading and overheating
I have been using A5 2017 model for last 2 yrs. Only recently I started facing battery drain issue. I thought it was because of many apps on mobile that eats up the charge. I uninstalled many apps. I did a factory reset. Issue hasn't resolved yet. Now I need to charge my device atleast twice a day.