If you just leave without giving notice (a runner) then your employer can attempt to file paperwork that will prevent you from getting a work permit for X number of years. I have heard this is difficult to do but I don’t have any specific experience with it. I later learned that I replaced a teacher that had done a runner but the school was unable to essentially get him blacklisted for X number of years.
Ultimately you should go down to your labor department and find out if they can legally withhold the pay if you leave early. imo these kind of clauses are complete bullshit especially when they conveniently omit them from the English portion of the contract and don’t talk about them when signing.