Did you get any further with this?
I managed to connect to it using nRF Connect android app - the output is mostly the same as you received from gattool. If I then fire up the AC Infinity app and bond it to the device, that 70d51002 characteristic gets a property of NOTIFY and the value starts updating every 1 second.
Also if I then tap into the graph tab of the ac infinity app, i get huge strings for the value here, updating very quickly - so I guess that is the historic information too.
I think a similar approach to this is needed here - ESPHome definition to pick up readings from the PH-260BD water PH/EC/TDS/Temp sensor - https://www.aliexpress.com/item/1005002707585119.html / https://www.aliexpress.com/item/4001143771176.html · GitHub
Maybe we can sniff the packets required to initiate this characteristic then get the sensor data broadcasting without the app also running. It does look like all the required pieces exist for this to happen, including writing data back for setting fan speeds.
I would be interested to hear from @itzyoungen about how your sensor data may have ended up in HA - guessing you had a bluetooth tracker of some sort running and opened the ac infinity app?
Not sure if any of this is useful, I’ll prod at it a little more tomorrow and attach a wireshark trace of what the app is up to.