Are you referring to the JST connectors? If so, those are not waterproof.

Also since each fan comes with its own wire, you always spare wires to revert back to. Here are the Amazon links if you need for reference to the terminals and crimper. jst sm terminal and the crimper

I had the same issues, and bought this kit: ( OCR 2.5mm Pitch JST SM Connector... https://www.amazon.com/dp/B071HFPXBD?ref=ppx_pop_mob_ap_share ) and I highly recommend this tool to get the proper crimp. ( Flytuo Open Barrel Crimping Tool,... https://www.amazon.com/dp/B096NN52GP?ref=ppx_pop_mob_ap_share ). Use the 2.5mm notch.

On my stock ender5+, they came with the black colored ones on the thermistor. They are the 2.5mm pitch jst connectors like these from amazon and you would need a crimper like this . They have worked well.

That said, I've had no issues with soldered connections with thermistor wires.