Protruding extra lines

Here’s what I think is happening.

I suspect your laser module is not well secured to the gantry. If you push the laser module forward and back against the gantry, is there significant movement? If so, use the eccentric nuts on the wheel shafts to close any gap between wheel and rail. You want to eliminate any gap but don’t overtighten as that can cause binding and other issues.
You don’t see the tail on the first letter S because it’s likely positioned well enough where this isn’t a problem.
However, you see it at the starting point of each subsequent letter when the laser module moves rapid from the top of the previous letter to the bottom of the next letter.
Because the laser module is flexing at this time it’s not in the proper position when the laser restarts. This is when the tails are being formed.
Once the laser settles down from the rapid movement things seems mostly okay.
If the laser module is not loose, then I’d suggest checking if the lens is potentially loose. That could cause similar issues.

There’s also the possibility that this is from backlash along the Y axis but that doesn’t seem as likely.