Sounds like you have incorrectly set up your machine, specifically the Z offset. Or your Z endstop is physically too low and not set up properly.
I'd suggest recalibrating your machine from the start as that would help dial it in as well as potentially solve this issue.
I recommend following this guide at the Teaching Tech 3D Printer Site \- it's extremely good. (there's also a page for troubleshooting different issues including testing your Endstops to confirm they are working)
Good Luck. 3D printers can be hella finickity but all in good fun.