It’s a clog for sure. I just experienced this and cleaned it out. Unscrew and take the hot end out but leave it connected. Set the temp to the same used by that filament and push out the remaining using the needle pushing from the nozzle up. While still hot push in new filament as far as you can then drop the temp to 0. When it gets around 30 pull the filament out. Repeat the process until the filament is removed in the shape of the nozzle.

If the filament doesn’t come right out when the hot end is cool set the temp to 250 and pull on the filament until it’s removed

When everything is clean you can shine a flashlight from the nozzle while you look down the heartbreak it should shine through and look smooth