The garbage collector and cycle collector are run all the time normally, so clicking on those buttons shouldn't have too much effect on memory when you are using the browser normally. They are mostly useful for getting to a settled memory state right after opening a page rather than having to wait a few minutes for it to naturally happen, or in the rare cases where a GC should be triggered but isn't.
As for why running the GC might increase RAM usage, I guess it is possible that some memory had been paged out, but running the GC causes the browser to touch all memory, paging it back in. That's just a guess though.
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The garbage collector and cycle collector are run all the time normally, so clicking on those buttons shouldn't have too much effect on memory when you are using the browser normally. They are mostly useful for getting to a settled memory state right after opening a page rather than having to wait a few minutes for it to naturally happen, or in the rare cases where a GC should be triggered but isn't.
As for why running the GC might increase RAM usage, I guess it is possible that some memory had been paged out, but running the GC causes the browser to touch all memory, paging it back in. That's just a guess though.