Powerpoint presentations are not fluid and stops suddenly on Mac running macOS Sequoia

What Mac? What external display (a projector, maybe)? How is the external display connected (HDMI? Airplay?)

Does it make any difference if playing back on the mac screen vs the projector?

Maybe there are some third party software modifications causing an impact.

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

The report shows multiple crashes in the same day. I don't know the cause, but it is unusual to have several system processes crashing multiple times.

I also noticed what appears to be Microsoft applications installed many times in the same day - that is weird (Word appears if it had been installed more than 10 times, for example). While this could be a glitch in the report, it's the first time I have ever seen something like it.

I see that at some point (May 9) you installed "cleanmymac". It appears to have been uninstalled, which is good. Do not install this or any other program that claims to "clean", "optimize" or "speed up" your mac. They're scams and cause your mac to crash. I wonder if, despite it being uninstalled, it may have caused damage already. It is known here in a not affectionate way "brickmymac"...

I don't often use Powerpoint, but I did a quick test, and could not reproduce the problem, in a machine identical to yours (2019 16" MBP), and in a current M4 Pro MBP.

It could be some issue with Powerpoint settings, or maybe an interference by some other third party software.

Etrecheck is a free diagnostic utility by etresoft, a frequent contributor and respected member of this community. It provides a report so that others here trying to help can look for issues.

You will find many of these reports if you browse the forum.