The next symbols is a number 4 forward and a number 4 written backwards.
The "M heart 8" puzzle was mentioned at some point in the movie "Oxford Murdèrs" (2008).
It basically is a capital M above a heart which in its bottom end is crossed by a straight line and beneath it is the number 8. This is a symbolic symmetry of some kind and you are supposed to find the next symbol that goes under 8.
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