Here is a summary of jhana to my knowledge:
Jhainc states correspond to the mental states in the brahma realms. The first four jhanas correspond to the rupavacara brahma realms and the higher jhanas correspond to the arupavacara brahma realms.
The jhanic experience is the same whether they are Ariya or anariya jhana.
The critical difference is the following: Kama raga (cravings for sense pleasures including sex) and patigha (tendency get angry) will be SUPPRESSED (vishkambana pahana) while in anariya jhana. But if one can get into even the first Ariya jhana, then kama raga and patigha would be completely REMOVED (no anusaya remain).
Therefore, if one can get into the first Ariya jhana, one is an Anagami.
In the same way, avijja is SUPPRESSED at the fourth anariya jhana, but is REMOVED at the fourth Ariya jhana. That means one is at or close to the Arahant stage if one can get onto the fourth Ariya jhana.
Therefore, only that person who is experiencing a given jhana can determine whether it is an anariya jhana or an Ariya jhana.
It is not necessary to have any jhana to attain a magga phala, including the Sotapanna stage.
On the other hand, one could be a Sotapanna and may have anariya jhanas.
There is nothing “bad” about anariya jhana. All jhanas are mental states corresponding to brahma realms, and one would be born in that realm at death. The difference is that one with an anariya jhana (without magga phala) will come back to human and even lower realms in the future. One with an Ariya jhana will never come back to the kama loka at all. A Sotapanna with an anariya jhana will also not come back to kama loka.
These are discussed in detail with sutta references at: ‘Mundane versus Supramundane Jhāna”. More details at: “Samādhi, Jhāna (Dhyāna), Magga Phala“.
Personally, I have not experienced the fourth jhana, where one is totally covered with white light (according to suttas). It is not that others can see that white light; that is what one in jhana “sees”.
I do believe that many people who have attained Ven. Abhaya’s meditation sessions have attained the fourth jhana (I have watched a few youtube videos where their experiences are described). But the question is how many of those are actually Ariya jhanas. Only those persons would know.
If any of your friends like to share their experiences, that would be great. Many people at this forum are not able to watch and understand those videos where jhanic experiences are described by the participants of Abhaya Thero’s sessions.