H1B transfer during pending petition

Quick question. My project ended on May 1, 2020 and my employer(Employer A) withdrew my H1B. I got an offer and will be joining it on 14 May once the new employer (Employer B) files for H1B transfer. I’m also in talks with another employer (Employer C) for a full time opportunity. My question is can I join Employer C if they offer me a job while my transfer petition is pending with Employer B and what would happen to the pending petition