Too many data points in a PowerPoint template generally make the audience confused to go through the content or listen to the presenter, thus leaving an uninterested audience.
Instead, use bullet points or pictures to convey your message, but make sure not more than 5 bullet points are covered in a single slide
Animations or slide transitions are nothing but tools of confusion, they take the audience’s focus out of the message and shift it into unnecessary drama.
So do not overcomplicate your deck, if you are persistent to use transitions make sure to use something simple like fade-in/fade-out, rather than disappearing squares or changing colors
The biggest mistake that can make your presentation look unprofessional is the use of different fonts across the complete presentation and not having a single-color scheme.
These pre-loaded templates come in very handy even to take care of fonts, color schemes, charts, graphs, graphics, content-appropriate infographics, etc. to give a proper visualization of the presentation story.