If you(or your distro) use zram then the zram usage may also count as swap in resource monitors. For me this was the case when i saw swap usage where it is clearly not needed to swap. You can check it with swapon commands.
Other reason is that more frequently accesed files may be cached to ram and less important stuff gets swapped. But if you notice swap being used while total ram usage including cached is much lower than total, then its probably zram(and it does write to disk so dont worry about that)
If you(or your distro) use zram then the zram usage may also count as swap in resource monitors. For me this was the case when i saw swap usage where it is clearly not needed to swap. You can check it with
swaponcommands.Other reason is that more frequently accesed files may be cached to ram and less important stuff gets swapped. But if you notice swap being used while total ram usage including cached is much lower than total, then its probably zram(and it does write to disk so dont worry about that)