TDLR for the other two comments: a Japanese mathematician is claiming to have a proof for it, but it is based on an entirely new very complex field of maths which he invented. Getting into it takes years, so other mathematicians are hesitant to invest that much time only to find out that the proof is broken and the field isn't otherwise useful.

It doesn't help that the author is rather withdrawn and not willing to spend any effort in making it more approachable.

Some tried, and said they found gaps in the proof, to which the author responded, but they were not convinced.

And that's essentially the situation since 2018.