At the start of parashat Behar, we encounter the following masoretic note. The text is slightly blurry, so I'll explain that the circle is over אל-הארץ and the masoretic note states ג' בטעם, meaning that there are three instances in which this particular trup occurs on these particular words.
Rabbi Yehuda Leib Shilslowitz, in the sefer Masoret haKeriah, writes as follows:
el-haAretz: The masorah upon it is ג' בטעם, and this is difficult. If it applies to the two words אל הארץ, are there not many with the trup of [zakef] katon. And if it applies to the four words, כי תבאו אל הארץ, there is no other with this trup, for all the other כי תבאו אל הארץ have the trup of munach revia [while this one has mahpach pashta]. Therefore it appears to me that we need to emend this to state לית בטעם [where the לית would have been written as a ל, easily confused by a scribe for a ג], and it applies upon these four words, that there is no other with the trup of mahpach pashta katon, for the rest have munach revia.
Update: Good spot by Aryeh S! He writes in the comments:
If you look at the Leningrad Codex up on archive.org - https://archive.org/stream/Leningrad_Codex/Leningrad#page/n145/mode/2up
are we so sure it says "gimmel b'taam"? It looks more like "gimmel b'SYPh", and if you look on the page before when the same phrase comes up, it says it again.
If thats correct, maybe it means to say "gimmel b'sefer", and in fact there are only 3 times in Sefer Vayikra that "ki tavo'u el haaretz" appears.
I dont know much about the Masoretic text so this is just a guess.