This is not typical A2 event which NW generally configure.
This is just the way of UE implementation to notify NW that something is wrong from UE side and release the secondary node.
Some UE vendor use SCG failure indication to convey the same to NW.
Actually what I have gone through is no threshold or way forward recommendation from OEM till now like you mentioned -140 as A2.
Hm ENDC Take back.
gNB OEM also enjoying this leverage to exclude SCG failure as normal and not considered as abnormal.
It’s just while sending A2 event, UE send this value -140 dBm.
Irrespective of whatever is current RSRP.
It depend on what cause of SCG failure UE sending.
If general one then eNB/gNB cannot differentiate normal or abnormal.
But if UE use A2 event (Like Samsung S21 do), its pretty normal for eNB and no Performance affected by it.
It’s about users experience, OEMs can hide incapability.
Plenty of handsets have the same behaviour after 20-25 min 5G uses switching to 4G.
A2 Event will remove SCG as normal cause.
But its not fault of RAN vendor.
But is there any study why NSA UE get heated so fast?
Is it due to higher BW of NR?
is it due to simultaneous uplink from NR and LTE and UE end up using more power?
Or both?
Any other reason?
And in SA also same issue faces by anyone?
It is due to long tests!
We have intensive drive test where UEs are challenged in hot summer and they get heated due to high download and upload, and YouTube and so on.
It is normal to get heated.
It is not normal that they release SCG 
I am talking about in personal use.
In personal use too.
You doo 4-5 ookla tests.
And that’s it : 5G is released.
True in India all can not afford to be AC.
In such case Serv. provide will keep on monitoring high 5G to 4G count and issue will be device or UEs.
But this is operational reason.
What is technical reason?
What is difference compare to LTE?
Is it higher BW/download/upload, multiple uplink and hence more power use? What else?
If above reasons are true, then in case of SA, if UE is good UL RF condition and with normal data activity like LTE, this issue would never occur?
For personal use I found it strange that even after 4-5 ookla tests the 5G is cut.
Those UE get overheated way too fast.
This should not happen.
Ohh. SA or NSA?
NSA
Just try yourself to do a speedatest for 4-5-6 times.
And after the 6test there will be no more 5G.
Due to overheating.
Is it Qualcomm or Exynos?
It is Exynos.
When 5G will disable, MSTC will be on?
Like in this 
Do you have experince of SA?
Sorry I do not know what MSTC is for 5G.
Anyone knows?
There is almost no data. I just want to see when 5G will be disabled for you, this one is on or not, because I experienced same issue.