Minecraft why glass panes no longer connect?

For some time now, no glass has been connecting in Minecraft, so you can still see the edges of the block. That was never the case before, what can it be? Play Java Edition 1.15.2

Maybe the texture pack created this transition because as far as I know the discs always have a line.

Panes of glass still bond when you use a current texture pack. If you notice this on a server, it has a viaversion and is originally in a lower version. Unfortunately, in the current versions, glass panes and fences are only lines. In that case change the version.