Recently I read (and can't find) an article that said there might be a situation in which running a 32-bit OS (and 32-bit programs) on a 64-bit OS would be preferable - if your system has 2 GB RAM or less. 64-bit processors can access more RAM (> 4 GB) which is great but that comes with a bit of memory hit.
Everything running (as well as programs/data that is cached) is some space in RAM. Programs have to know how to access that RAM so each chunk of data has a starting address. That'd be like addresses on a street with the data being the people and things in them. But you also need to know where to find that data. That'd be like a phonebook. You need to find someone, it tells you where they are (or should be during a pandemic).
A 64-bit OS can not only store longer addresses it has to even if the address wouldn't normally need the space. Think of a phonebook that used to have 4 columns but now some people live at 8938493893493489 Lundy's Lane and they have names like John Iljieafiejliaifejeoigiggmmg instead of John Smith, so the phonebook can only have 2 columns now. There are lots of shorter names and shorter addresses but that doesn't matter. They all need that larger space now. The phonebook has doubled in size even if only 20% of those addresses actually need double the amount of space. Of course, that's assuming the same font size. But for the analogy, it would have to, because we can't make bits in a computer take up less room. So just like we need more pages in the phonebook, we need more RAM now just to store those addresses.
Someone told me years ago that if you're using 8 GB of RAM, 1 GB alone is used to store the addresses (assuming you're using nearly all of the RAM). That's no big deal on systems with lots of RAM. But if you only have a system with 1 GB of RAM, you don't want to give up 125 MB just for storing addresses that you don't actually need. So a 32-bit OS (which means 32-bit programs, too) is better for such a system. This might be why the Raspberry Pi 3 (and I believe the previous models) used a 32-bit OS even though it was capable of running a 64-bit one. With Pi 4, you have at least 4 GB of RAM so you can afford to use that extra RAM.