The temp control on your iron sounds busted/mis calibrated; it shouldn't be eating through tips like that, and lead free solder requires around 400C. You say 250-300F, so either your solder ISNT lead free and you got scammed, or your temp control is busted/heavily mis-calibrated.

Your solder gauge is wayyyy to thick for the power of your iron, yours looks like a 60W-80W iron, use like 0.6-1mm solder guage.

Finally, use a WET sponge, not dry, and tin your tip ONCE at the start and end of each soldering session, then wipe off the excess with the WET sponge.

Here's a digital iron: https://www.amazon.com/Soldering-Digital-Welding-Portable-Electric/dp/B08R3515SF/ref=sr_1_2?crid=28FP9LV92LCAF&keywords=digital%2Bsoldering%2Biron&qid=1685156536&sprefix=digital%2Bsolder%2Caps%2C120&sr=8-2&th=1

Should be better than your current one.

If you are using those craptastic 3 cent inserts, testing (CNC kitchen), has shown them to be weaker than no insert.

You don't need the "best" iron. You can get a temperature controlled soldering iron for around $15 on amazon with the temperature controller built into handle. Don't spend a lot on one you will be misusing. https://smile.amazon.com/Soldering-Digital-Welding-Portable-Electric/dp/B08R3515SF/