I don’t know how to read that chart. How do we know the levels increased? What did they used to be? who operates that site? What are safe levels?
Particularly concerning are some near the reactor building itself that went to a fairly high reading very quickly (65500 nSv/h in one case, which is likely offscale high) and then stopped reporting at 21:50 local time (it's currently 03:30).
65500 nSv/h is definitely not 'you're going to die right now' radiation levels, but it's definitely getting into the territory of stuff you don't want stand around in for too long. If I've done the math right, I think that's about three times the allowed annual exposure for radiation workers every hour.
Edit: I think I didn't do the math right and am off by 1000x. 65500 nSv/h is like three chest x-rays an hour. Which is still not good, but would take quite a bit longer to get really dangerous.
65500 = round(typemax(UInt16)/100)*100
and no higher value exists on the map it might actually be worse how much we can't tell though.
However, since you've chosen to communicate through code, strictly speaking it ought to be '==' :p
However, in practice yearly 'safe' limit for civilian population is 20 mSv (ref: https://www.stuklex.fi/en/ohje/ST7-2)
The map is nSv /h. Lets take dot with 2000 nSv/h. In order to obtain yearly limit you need to hang around for 10 hours. Whereas 65000 area would be around ~20 minutes.
Please bear in mind that this is gross simplification.
2000 nSv/h * 10 hours = 20 μSv (microsieverts) = 0.02 mSv (millisieverts)