While heating, BLTouch mesh data gets worse and worse the more times you probe
It looks like the changes are always going in the same direction for a given probe point (each point increases steadily or decreases steadily, there is no oscillation).
This means that the bed is not warm yet and you should wait longer.
In theory the heating of the BLtouch itself may affect the readings, and the air surely gets progressively warmer around it, but since some values increase and other ones decrease, that's not the cause.
The values change because the bed is still adapting to the temperature increase.
For a more systematic and scientific approach, do the following.
With the bed cold, heating off, probe a single point 10 times without any delay, then put the data in a spreadsheet and calculate the standard deviation, to know how accurate the sensor is.
After that probe the whole bed every 5 minutes during heating for half an hour and then plot the values on a graph (each point separately). At a certain point you will see that the values will oscillate about as much as they did when the bed was cold. That is the time you need to wait for proper bee heating. Different parts of the bed may reach the temperature in different times, that's why each probed point has to be graphed separately over time.
If you use an enclosure, as you do, the continuous change of BLtouch output can also be dependent on the overall heating of the printer frame and structure: instead of heating only the bed, in an environment which stays the same, you are heating the whole environment through the bed. It becomes more complex. The BLtouch may be fine, but you may need to keep heating it until the readings stabilise.