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no do not remove anymore. old leaves take the brunt of a problem. if you remove them the problem just advances faster to the next leaf. looks like a burn of some sort. did you splash nutes on them? overall they look very healthy I would not worry just keep an eye on them.
if you have mites, you would have stains on your leaves...some brown like on your picture and some other would be light green...older and newer...
you would see really tiny black dots around the stains...
also see some tiny webs on the edge of leaves and on their back....the ones on the edge are easier to spot...in the sun light...move your leaves to have the light reflect on webs...it can be quite unoticeable
it is the case for me now...your leaves on the pictures look a bit like mine...but as lokes said