In this passage, Oliver Cowdery initially wrote “the way of the Lord”; then later, with somewhat heavier ink flow, he inserted the plural s, giving “the ways of the Lord”. This correction appears to have occurred when Oliver proofed 𝓟 against 𝓞 since nearby corrections in 𝓟 also involve a somewhat heavier ink flow (see, for instance, the discussion under Moroni 8:5–6). Thus here in verse 16, the original manuscript probably read in the plural.
In the Book of Mormon, the phrase “the way(s) of the Lord” always takes the singular way when the verb is prepare (six times, as in 1 Nephi 10:7: “and he spake also concerning a prophet which should come before the Messiah to prepare the way of the Lord”). This language can be said to derive from the language in Isaiah 40:3: “prepare ye the way of the LORD”. On the other hand, if the verb is walk, then we always get the plural ways (four times, as in Mosiah 6:6: “king Mosiah did walk in the ways of the Lord”). There are also four unique uses of “the way(s) of the Lord”, each of which takes the plural:
It turns out that only one verb shows variation, namely, pervert. In all, there are ten more instances of “pervert the way(s) of the Lord”, of which two take the singular way (each of these is marked below with an asterisk):
There is a third instance of singular way that we could add to the list (here we have “the right way of God” rather than “the right way of the Lord”):
Interestingly, the first example listed above (in 1 Nephi 13:27) reads ways in 𝓞, but in 𝓟 Oliver Cowdery initially wrote way before correcting it to the plural. The same error seems to have occurred here in Moroni 8:16 for 𝓟: Oliver initially wrote the singular way but corrected it to the plural when he proofed 𝓟 against 𝓞.
Thus the textual evidence supports the occasional use of the singular way when the verb is pervert. So for each case of way versus ways, we follow the earliest reading. Here in Moroni 8:16, the plural ways appears to be the original reading.
Summary: Maintain the plural ways in Moroni 8:16, the corrected reading in 𝓟 and the probable reading in 𝓞, no longer extant for this part of the text.