if your solar panel is permanetnly attached to the battery there is a slim risk the battery will boil. Not fun.
Most likely when you attach the panel to the battery, the voltage will go down to something close to the battery voltage (.. as it was before you attached). this is hopefully ~12.5 V. Slowly, as the panel is a small one, voltage will increase.
Maintenance charge voltage is in the range 13.5 - 13.8 V (about, let's not go to deep here). It is OK as long is you are not exceeding this.
Fast charge voltage is ~14.5 V. Above that is certainly not good at all. Here ae are talking boiling.
With your small panel, and a battery of ? 100 Ah? 75 Ah? there should not be any risk to have a semi-permanent attachent, but then I am speaking from experience of a very dark country (but not in the summers
). In any case, I would not leave the panel attached for moths without monitoring now and then.
Using a regulator (which I do, but then I have close to 100 W of panels) consumes some of the energy. Unavoildable. Small and cheap ones are close to worthless; I had one such, wasted $150 ...
So either you get a good one, which is likely to cost, or you live happily with what you have and keep an eye on things.
Another view: PO seems to have used it intensively.