Welcome to the club! It sounds like you know what to search for, so you're off to a good start. If you haven't found it already, Ellis' print tuning guide will give you a good foundation for tuning your printer well.

It looks like you have an Ultrabase bed, or at least something very similar. I had one on my i3 clone and it served me well for a number of years.

As you discovered, prints will stick to it well if it's clean. Dish soap and IPA (use the 90+% stuff) do a decent job of cleaning it. Windex also works well for keeping it fresh. Prints will easily release after the bed is cool, especially after the bed gets some miles on it. I'm betting the prior owner either had trouble with their first layer sticking or releasing - glue sticks are used by some for both scenarios. Proper first layer squish, a slow first layer, a clean bed, and a cool bed are all it really takes unless you're printing something like ABS/ASA and then your first step should probably be an enclosure, not an adhesion promoter.

What tool is it that you printed?

I have that exact printer, and it's an absolute champ.

One tip that might sound stupidly obvious, but when the printing is done, let the bed cool down fully before you try to remove the print. 99% of the time, you'll hear an audible 'pop' as the print detaches itself automatically. I've never had any need to ever use a scraper on it.

Contact cleaner is just saltwater, it does lead to one part of the bed getting cooled faster than the rest, which over time doesn't improve the bed.

Just wait for it to cool and peel it off and it should be fine from here out.

Spraying conductive saltwater near powered electronics is something I do not recommend.