Just stab this thing a couple of times and you should be good, the brass cleans it off without doing much damage to the tip.
https://www.amazon.com/Weller-WLACCBSH-02-Soldering-Cleaner-Silicone/dp/B08FQBS97L
This is a case where cheap is perfectly fine. Just needs to be brass. I use this in place of / in addition to wet sponges.
You can also use a large wad of aluminum foil, loosely crushed into a ball. Just insert the hot tip and lightly scrub off the gunk. Then, IMMEDIATELY tin the tip. (Melt some solder on the entire tip and then gently remove the excess.)
You might also benefit from tip cleaner. Use this stuff sparingly. It's not an everyday use item. Its not actually that great for the tips, but used sparingly and infrequently, can help restore an otherwise unusable tip. Use with ventilation. It stinks. Haha
Weller 0051303199 Tip Tinner Lead Free.8 Oz, Black
Final note: the items above should be part of your toolkit regardless. But in this case, I'd get new tips or upgrade to a new solder station with good heat control.