I believe I saw the similar bird yesterday, but I was not able to take any picture.
I originally thought it was either Bianchi's or White Specticle Warbler when I saw it, without noticing the wing bar. I was not able to notice all the details of the bird with just 2-3s.
Recalling my memory from yesterday, I remembered the grey colour of crown did not extend to the front of the head. The black strip appear less dark in the background of grey colour. I agreed that it is Plain-tailed Warbler as well.
