Wrong. One Senator and One representative object but both chambers do not have to vote. Show me a single source for that claim, that both chambers must vote to throw it to the house... it doesn’t exist.
Try searching:
What can happen is the Senate and House agree to refuse votes from both sets of conflicting electors from say Georgia and WI, but accept PA and MI, or vice versa. Either way Biden still wins.
"But if the two Houses shall disagree in respect of the counting of such votes, then, and in that case, the votes of the electors whose appointment shall have been certified by the executive of the State, under the seal thereof, shall be counted."
I found this account of what happened in 2005 when Democrats objected to the inclusion of Ohio’s electoral votes.
https://www.cnn.com/2005/ALLPOLITICS/01/06/electoral.vote.1718/
“If one member of each body of Congress objects, congressional rules require that lawmakers return to their chambers to vote on the merits.
“A simple majority vote in each chamber would overturn the challenge — something that should be easily achieved in the GOP-controlled Congress.”
https://www.cnn.com/2005/ALLPOLITICS/01/06/electoral.vote/
“Alleging widespread ‘irregularities’ on Election Day, a group of Democrats in Congress objected earlier Thursday to the counting of Ohio’s 20 electoral votes.
“The challenge was defeated 267-31 by the House and 74-1 by the Senate, clearing the way for the joint session to count the votes from the remaining states.”
So in 2005 the vote on whether or not to count electoral votes that were objected to was done by simple majorities in both the House and the Senate. I would expect the same procedure to be followed in 2021.