H1b Transfer Risk? Rejection?

I am looking for a job change and thinking of changing my employer as well. As with this H1b transfer isn’t possible in premium now (Due to Corona) what could happen if my employer change petition gets rejected due to any reason and My employer in the meantime has withdrawn my petition?

My initial I-94 is approved till Jul-2020. Please tell me what could happen if that rejection comes before and after that month.? Also please tell me if that 60 day grace period can help me here?

Thanks in Advance.!

You need to leave the country, if you get denial. The reason is you would lose your valid legal status on the day you get denial and cannot apply for any COS.
If your old employer has withdrawn or your I-94 expired, you are fully out of options and have to exit the country… The grace period only help, if you lose your job, not here.