You certainly have a lot of PHP versions there. That is almost never a good idea. Why did you install so many? Most people only need one version (most apps work in all the current versions), and almost nobody needs more than one of each major version (you have four 7.x versions and two 8.x versions, that’s crazy!).
But, that’s still just guessing. You need to look at what’s actually using memory on your system. You can look at the process list in Webmin, or you can look at top (I prefer top) or htop on the command line and sort by memory.
You can’t guess your way out of problems like this. You need to gather useful data, and then make an assessment of what needs to change.