This situation is very common, and the time of occurrence is often during the first court investigation, especially before the end of the court investigation, the judge will imply or directly inform the plaintiff of a meaning: there is a problem with your claim, whether to change the claim, and ask you to determine whether it is a previous claim or a change of claim. Of course, the judge generally won't say that you can't win if you change your claim.
As long as the judge reveals in court that he wants you to change the claim, then the deeper meaning is that your evidence cannot prove your claim, or your claim itself has no possibility of winning, and if you do not change it, you will lose the case or even lose the case completely. Then you have to choose one of the two options, whether to withdraw the lawsuit or change the claim.
If you think the claim is okay, but the evidence is insufficient, but you think you can find a way to supplement the evidence. Then you can consider withdrawing the lawsuit and prosecuting the lawsuit when the evidence is sufficient.
If you feel that there is a problem with the claim, or if the claim is okay but the evidence is insufficient and it is difficult to gather evidence, then you may consider changing the claim.
Summary: In civil cases, it is very common for a judge to request a change of litigation, and you should actively respond to it according to the above two logics.