Self citations are fine provided they are performed rationally or relevant to your current research / manuscript writing rather than merely bias toward your published papers or set with an intention to merely "market" your published papers.
from the viewpoint of intellectual property rights it is absolutely correct to cite yourself when you are the first who published a special topic in your own papers. Anyway you should take care that you are really the the creator of the contetnt you cite. That might be sometimes difficult and not your intential mistake. But I think there are a lot of possibilites to correct it later on when following up the topic in your papers.
With best regards
Michael
P.S. This subject was the reason why I started the project https://www.researchgate.net/project/SCIENTIFIC-LITERATURE-40-examplarily-for-Carbon-Fiber-Research
I add for the reverse case, when there are very few self-citations, means that there are no connection nor continuity with previous works. The researcher jumps from a subject to another, ....!
Self citation is normally observed in most of the research papers. This is essential because it gives idea about status of present research work with previous work in the same area by the same researcher. Some times it helps in linking the research activities and gives proper direction to the long term research work . Indirectly, self citation is indication of an area of interest of the researcher. Actually , self citation should also be counted for determining citation index.
Any citation is only appropriate when it is 'relevant' to the article being written. If you work in a subfield which is populated by only a few researchers, then you will likely end up citing your own articles a lot. This is not a bad practice, just a result of the fact that you are a major contributor in that area.
A similar topic to this has been discussed recently on Researchgate. See more comments here: https://www.researchgate.net/post/Self_citation_is_it_ethical_or_necessary_sometimes
I think this way is very important to confirm your professionality in such research work and to avoid any dought for overlapping of that submitted work with other published one.
Any citation is only appropriate when it is 'relevant' to the article being written. If you work in a sub-field which is populated by only a few researchers, then you will likely end up citing your own articles a lot.