Meticulous but Inefficient Superior

I downgraded my role in my current job as an associate because I was drained being in a supervisor role in my last job (6 months lang naman yung tinagal ko as sup). Pay is still higher because of my skills. Workload and responsibility is also lighter than my previous job and it is also WFH so, why not accept this JO diba?

But now I'm kind of regretting it because of my immediate superior. I am used to a fast-paced work environment and I know how to catch up with deadlines, so him being so slow bothers me. He's so meticulous to the point that our work is now inefficient, we are behind our client's deadline and budget. The client clearly told us what to do straight to the point work - but my superior is sobrang bida bida ba, he wants to go over and beyond. He wants to add this and that to our project (which is time-sensitive btw) that results to too much revisions and inefficiencies. Now our client wants the work done by next week but my superior is not taking my suggestions seriously of cutting down on those additional work that he wants, maybe because I am just a newbie and he is always right in our leader's eyes. My senior manager trusts this supervisor so he also listens to only what my supervisor says.

Now we have a meeting on Monday with the client and idk how to really deal with this situation.