DB_schema's journey

I was recently laid off from Microsoft on August 21 while on STEM OPT, and my cap-subject H-1B change of status is pending in premium processing with an October 1 start date. I'm reaching out to see if anyone has experienced a similar situation and can offer advice. I'm considering asking Microsoft if they could extend my official employment date by a few weeks or delay withdrawing my H-1B petition. If they refuse, I'm worried about whether a new employer could use this year's H-1B selection or if I'd have to go through the lottery again. Any insights or experiences would be greatly appreciated!