I am relatively new to academic publishing. However, there is an uncomfortable situation which I have already encountered multiple times by now (about five). It is what I would call "low-key plagiarism". I will explain what I mean by this (completely made-up) term in the following.
I don't have many papers and citations yet, so I tend to check out papers that cite me to see how my work is being used and if the new result is relevant to my own work. In the mentioned occasions, I found that the authors used my work extensively or built directly on it. The way the citation was phrased, however, implied that my result was only tangentially relevant or somewhat helpful. Sometimes the relevance is also disguised by citing further irrelevant literature.
The goal of the authors in both cases seems clear: to mislead a reviewer or readers into thinking the result is more significant or innovative. Of course, an ideal reviewer should spot this. However, in highly specialized fields and if the formulation is sufficiently vague, this is very difficult and does not happen practically.
I am not sure if this should really be called plagiarism. It is the kind of borderline case where, most likely, nobody will bring up the argument publicly. If someone does, the authors will most likely say "but we cited you here and there". No matter if plagiarism or not, it is certainly misleading to reference in this way.
When I find a citation like this, it feels very uncomfortable to me. Especially for interdisciplinary research, people might start citing the newer result and forget the older one completely if the citation chain cannot be tracked properly. This is the exact same effect as completely leaving out the citation (i.e., plagiarism) would have.
How can I deal with this kind of misleading citation practice? Should one just get over it? Should one contact the authors to express disappointment without asking for consequences? Should one fully escalate and demand a correction or bring the editor's attention to it? Should one do it even if the chance of success is low and the chance of hurting one's own reputation by being perceived as petty is high?
As suggested by Dan Romnik, I've tried to come up with a fictionalized example for what the misleading paper might be saying. The example contains three tricks which I have encountered on separate occasions. 1. List citations to hide relevance. 2. Shifting the citation to a supplement and omitting the citation in the main text summary of the method. 3. Attaching the citation to a meaningless side sentence instead of to the main result.
Here is the example: Let the main text contain no reference to the paper, except for a bit in the introduction citing it as previous literature as part of a list citation. Instead, it is stated in the methods that
We derive our main result using some abstract formulation of the method for brevity.
The method summary thus misses the citation, which is shifted to a supplement.
In the supplementary material, it is stated that
Introductory discussion to notation. Eq. (1) coming straight out of my paper. We derive our main result based on this equation by solving some integrals for a special case. This includes a completely standard step, which was also investigated in . Our result is then obtained this way: concrete formulation of the method which was abbreviated in the main text and which is a special case of my method.
where  is my paper. Therefore, even if the reader looks in the supplementary material, they will not know that the central Eq. (1) is straight from my paper. The citation is there, but attached to a completely meaningless side-sentence. Of course, a careful reader could go and compare the two papers, but without that, it is not clear how the result was used.
Even if the example is not great, maybe this gives an idea of what kind of tricks I mean. One of those can be accidental; in sum, they are likely intentional and designed to mislead. They certainly do mislead, but are they plagiarism?