I use soil meter to test PH and it will read different based on moisture content.
Very dry or very wet like just before needing watered or right after watering won’t give you accurate readings. Your soil is best to be tested when it’s in the middle range moisture wise.
I check them a day after watering and the top 3” reading will be the highest say around 6.8 then at 6” will be around 6.5 and at 9” will be around 6.2 or so. If I check when it’s too wet or too dry the same plant the readings won’t be the same. I have 2 of these meters so I am able to verify things if needed. I also have one of those $12 3 way meters and they will read very close to what the $50 meter reads as long as you take care of them and clean them after every use and not leave them in the soil too long they work fine you just need to make sure the moisture content is medium when checking. The wizard meter also has moisture check and as long as the moisture is in the 3-8 moisture range it reads fine.
When your done with your meter wipe it off clean and then use green scratch pad like for dishes etc and lightly clean off the probe top to bottom to keep it from oxidizing etc. I also give it a quick wipe with pad before using too.
Here is a link to a write up I did awhile back on soil meters.
Hope this helps with that part of your grow