Stash tab highlight items search quary: '+' symbol is no longer processed correctly!

I have just noticed that recently working method to highlight all items having quality worked as intended, e.g.:

"Quality: +20%"

highlights all items (e.g. gems) having 20% quality.

However now, for some reasons the "+" symbol alone does not highlight anything at all.

By using trial and error I have founded out that this symbol is still accessible using \ - like escape sequence:

"Quality: \+20%"

Is it the intended behaviour or bug? I think it is not obvious to use "\+" instead of "+" symbol.

another thing:
if search query e.g. "molten" highlights an item than "mol+ten" also highlights it, but "mol++ten" does not highlight it.