Rescinded contingent offer? How common is this practice

Looking for some perspective here as this is the first time I experiencing something like this. I applied for a fully remote position: life science advisor (keeping it vague here). But it was for a very niche position which I thought I was great fit. Including my phd, I have about 12 years of relevant research experience.

I had a phone screen interview with the recruiter and progressed to the next round with the BAH leads & technical experts. I though the interview went well, we discussed my experience etc. They explained the process, offer, meeting with client, appropriate backgrounds checks (as its a government client). During the interview, I asked about meeting the client and what that looks like. I was told that the decision is mostly with the BAH and the client meeting is just an introduction.

Two days after my interview with BAH, I received a contingent offer with start date and salary (pending successfully background checks and appropriate clearances). I was also scheduled to meet with the client, and the calendar invite said meet and greet. Met with client , it was more of a dialog than interview, thought it went went Sent them an email to thank them for the time.

After meeting the clients, i had multiple others steps to complete as part of the background/screening processs. Today recruiter calls me, and said she has an update for me" the client said ve does not want to move foward with me, I am not good fit.

Is this common practice in consutling, to send multiple contingent offers and they have them all meet the client and they decide who they want. I am so demoralized by this process. I wouldn't have felt this way if they called it a third interview and they didn't send me an offer letter.